As the author states and i quote "I fear no criticism as long as I am defending the correct Islam and distancing its noble Prophet from every error, even if that is at the expense of criticizing some close companions..."
I will copy part of the chapter since it is long and the rest you can read on the link i have copied:
As discussed, the ahl al-sunna wa'l-Jama'a permit no criticism or condemnation of any of his companions and maintain the belief in their collective uprightness. If any free thinker writes about them and undertakes to criticize the deeds of some companions, they defame him; in fact, they deem him to be an unbeliever even if he is amongst their own scholars. This is what has happened to some of the free thinking Egyptian and non-Egyptian scholars like Shaykh Mahmud Abu Rayya, author of "The Lights on the sunna of Muhammad" and "Shaykh al-Muzayra", and like Qadi Shaykh Muhammad Amin al-Antaki, author of "Why I chose the school of ahl al-bayt", and like Sayyid Muhammad b. 'Aqil who composed the book "The complete advice for [he] who befriends Mu'awiya". Indeed, some Egyptian writers labelled Shaykh Mahmud Shaltut, grand Shaykh of the University of Azhar, an infidel when he issued the ruling that it was permissible to worship according to the Ja'fari madhab.
If the grand Shaykh of Azhar, the mufti of all of Egyptian schools, is despised for merely recognizing the Shi'i school which is traced to the teacher of the scholars, Ja'far al-Sadiq (A.S.); then what do you think [they would do] to one who chooses to follow this school after research and conviction, and undertakes to criticize the madhab he used to follow, having inherited it from his fathers and forefathers? This is what the ahl al-sunna wa'l-Jama'a will not permit, for they consider it as heresy in religion and going out of [the fold of] Islam; as though Islam is, in their reckoning, the four madhabs and everything else is false. These are petrified and stagnant minds resembling those minds which the Qur'an talks of, and that which the Prophet's (P) call encountered. It defied him intensely, for he invited them to monotheism and abandoning the numerous gods. The most High says: "And they wonder when a warner comes to them from amongst themselves, and the unbelievers say: "This is a lying sorcerer, has he made all the gods as one? This is a surprising thing" (38:5).
I am safe from the malicious attacks that will be directed against me from those zealous persons who have kept themselves in authority over others. [To them], no one has the right to oppose their writings even if his writings do not take anything away from Islam. Otherwise, how could one who criticizes some of the companions be judged to have gone out of [the fold of] Islam and [become] a disbeliever when the foundations and branches of religion does not have anything [to do] with that?
Some fanatics were propagating amongst themselves that my book "Then I was Guided" is like Salman Rushdie's [work], in order to prevent people from reading it and so as to encourage them to curse the book.
This is a plot, forgery and great slander which the Lord of the Worlds will account for. How can they compare "Then I was Guided" which calls to the belief in the infallibility of the Messenger (P), his being beyond reproach, and [calls for] the following of the Imams of the ahl al-bayt from whom Allah has removed all filth and purified completely, with "The Satanic Verses" in which its accursed writer reviles Islam and the Prophet of Islam (P) and considers Islam is [due to] the inspiration of the devils?
Allah says: "O you who believe! Stand firmly for justice and bear witness for Allah, even if it be against yourselves" (4:135).
Due to this noble verse, I care not except for the pleasure of Allah, Glorified and Exalted be He, and I fear no criticism as long as I am defending the correct Islam and distancing its noble Prophet from every error, even if that is at the expense of criticizing some close companions, even if they were among "the rightly guided Caliphs", because the Prophet of Allah (S.A.W.) is more worthy of distancing [from error] than any mortal.
The unbiased, perceptive reader will understand from all my works what is my desired goal for the issue is not to denigrate or degrade the companions, it is to defend the Prophet of Allah (P) and his infallibility, and to defend him against the misconceptions which the Umayyads and the 'Abbasids cultivated about Islam and the Prophet of Islam during the early centuries when they ruled the Muslims with tyranny and force, changing Allah's religion according to what worldly goals, base politics and evil desires dictated.
Their major plots have influenced a large segment of Muslims who followed them out of good intentions towards them and accepted all the distortions and lies they narrated, assuming them to be true and to be a part of Islam; and that it was obligatory on every Muslim to follow them, not to question [them].
Were the Muslims to know the truth of the matter, they would not accord any importance to them or to their narrations. Had history narrated to us that the companions obeyed the commands and prohibitions of the Prophet of Allah (P) and had not argued with him or opposed his judgments, and that they did not disobey him in numerous rulings during the last days of his life, we would have judged all of them to be upright and we would have had no such scope for discussion or speech [against them]. However, amongst them were liars, hypocrites and corrupt ones, according to the Qur'anic text and the authenticated correct sunna.
They disagreed [with each other] in his presence and disobeyed him in the matter of writing [the testament] to the point that they accused him of hallucination and prevented him from writing. They did not to follow his commands when he appointed Usama over them. They differed on his Caliphate to the extent that they neglected his washing, preparation and burial arguing, instead, about the Caliphate. Some of them were happy about it and others rejected it. Indeed, they differed on everything after him until they accused each other of disbelief, cursed each other, fought and killed each other, and dissociated from each other. [Due to this] Allah's one religion split into different sects with divergent views.
Given this situation, it is necessary, therefore, that we search for the cause and flaws that made the best and most desirable of nations created for man to decay; it became the lowest, most ignorant and debased nation on the face of the earth, it's respect destroyed, sanctity defiled and its people colonized, banished and evicted from their lands; they could not defend [themselves] against the transgressors nor could they remove the shame on it's face.
The sole cure for this difficulty, as I see it, is self criticism. Let us forget the praising of our forebears, our false glories which have evaporated and have become ruined museums, empty even of visitors. The reality calls upon us to examine the reasons for our maladies, our remaining behind, our fragmentation and our failures, until we discover the disease and identify a beneficial cure for our well being; before it overcomes us and affects the last one of us. This is the desired goal, Allah is the only one worthy of worship; He is the guide of his servants to the right path.
And as long as our goal is a correct one then there is no value to the opposition of those fanatics who know nothing except insults and slander in their arguments for defending the companions. We will neither rebuke nor hate them after observing their situation, for they are deprived, misguided by their good intention for the companions. This has prevented them from arriving at the truth. They are like the children of the Jews and Christians who have trust in their fathers and grandfathers and do not impose upon themselves [the task of] research in Islam; relying, instead, on the utterances of their predecessors, that Muhammad was a liar and that he was not a Prophet. Allah says: "The people of the book went astray only after clear signs came to them" (98:3).
With the passing of successive centuries, it has become difficult for a Muslim today to convince a Jew or a Christian of the Islamic creed, what if someone tells them that the Bible and Torah in circulation are forgeries and proves that by the Qur'an, will this Muslim find a sympathetic ear amongst them?
Similarly with a simple Muslim who believes in the uprightness of every companion and is zealous about it with no proof. Is it possible for anyone to convince him otherwise?
If they are not able to find fault and criticize Mu'awiya and his son Yazid, and there are numerous others like them who distorted Islam by their evil deeds - what if they are told about Abu Bakr, 'Umar and 'Uthman, the truthful one, the distinguisher, and one whom the angels are shy of? Or of 'A'isha, mother of the believers, wife of the Prophet (P), daughter of Abu Bakr, whom we have discussed in the preceding chapter of how the reliable authors of the Sihah works, according to the ahl al-sunna, have narrated from her? Now we have reached the stage of the role of the three Caliphs. Let us discover some of their deeds which the Sunni Sahih and Musnad and reliable historical works have recorded against them, so that we can illustrate firstly that the concept of collective uprightness of the companions is incorrect, and that righteousness was missing even from [some] close companions.
Secondly, we will illustrate for our ahl al-sunna wa'l-Jama'a brothers that these criticisms do not amount to insults or slander or denigration, rather, they are means of removing the veils so as to reach the truth, and that they are not inventions or lies of the Rafidis, as most people claim. On the contrary, they are narrations from books that have been judged to be correct and they have obligated themselves to [accept] it.
In volume 6 page 46 of his Sahih, in "The Chapter on the Interpretation of Sura al-Hujurat of the Qur'an", al-Bukhari relates that Nafi' b. 'Umar reported from Ibn Abi Malika that "The two pious ones, i.e., Abu Bakr and 'Umar (R.) were very nearly destroyed, for they raised their voices in the presence of the Prophet (S.A.W) when the delegation from Banu Tamim came to him; one of the two recognized [as their leader] al-Aqra b. Habis, the brother of Banu Majasha, and the other recognized another person. Nafi' said: 'I don't remember his name' whereupon Abu Bakr said to 'Umar: 'You only wish to contradict me'. He replied: 'I did not wish to contradict you'. And their voices rose [in argument] over that matter, and Allah revealed: 'O you who believe, do not raise your voices ...'. Ibn Zubayr [later] said: 'After this, 'Umar's voice was not heard by the Prophet to the extent that the Prophet (S.A.W.) had to ask what he had said. And he ['Umar] didn't mention [the matter] about his father, I mean Abu Bakr'".
Similarly, in volume 8, page 145 in "The Chapter concerning Adherence to the Qur'an and the Sunna" under the heading of "What is Disliked about getting Embroiled [in Argument] and Contention" al-Bukhari relates: "Waki' informed us from Nafi' b. 'Umar from Ibn Abi Malika that: 'The two righteous ones, Abu Bakr and 'Umar, were nearly destroyed when the delegation of Banu Tamim came to the Prophet (S.A.W.). One of them pointed to al-Aqra b. Habis al-Tamim al-Hanzali, the brother of Banu Majasha, and the other indicated someone else. Then Abu Bakr said to 'Umar: 'Surely, you only wish to contradict me'. 'Umar said: 'I did not wish to contradict you'. And their voices rose in front of the Prophet (S.A.W.), and the verse was revealed: 'O you who believe, do not raise your voices above the voice of the Prophet nor address him the way you do each other lest your deeds be in vain and you perceive not. Those that lower their voices in the presence of the Prophet, they are those whose hearts Allah has tested for piety; for them is forgiveness and a great reward'".
Ibn Abi Malika said that Ibn al-Zubayr [later] said: "Thereafter 'Umar didn't mention the matter regarding his father, i.e., Abu Bakr, and whenever he spoke to the Prophet about something, he would do so in a whisper and could not be heard to the extent that the Prophet had to tell him to speak up".
Similarly, in volume 5, page 116 in the "Section on Military Campaigns (the delegation of Banu Tamim)" al-Bukhari in his Sahih relates from Hisham b. Yusuf, on the authority of Ibn Jurayj, who informed them, on the authority of Ibn Abi Malika, who related that 'Abd Allah b. Zubayr informed them that a delegation from Banu Tamim came to the Prophet (S.A.W.), and Abu Bakr said: ìMake the chief al-Qa'Qa'a b. Ma'bad b. Zuraraî and 'Umar said: "Rather, select al-Aqra b. Habis". Abu Bakr said: "You do only wish to contradict me", and 'Umar said: "I did not wish to contradict you". And they argued until their voices had risen, and the following verse was then revealed: "O you who believe! Do not put yourselves forward between Allah and his Apostle..."
It is apparent from these narrations that Abu Bakr and 'Umar did not behave in a proper way, i.e., in accordance with proper Islamic conduct in the presence of the Prophet (S.A.W.) and allowed themselves to advance in front of Allah and His Prophet without permission; nor did the Prophet of Allah (S.A.W.) ask for their views in appointing anyone from Banu Tamim as a leader; then, they were not content until they were arguing in his presence and their voices had risen in front of him (S.A.W.) with no respect or care for what is customarily decreed by good character and morals, values of which none of the companions could have been ignorant and which they could not have ignored after Allahís Prophet (S.A.W.) committed his life to their education and upbringing.(The rest can be read on the link listed above)