I also got that impression from his interview with Rachel Maddow. I also think he screwed up the email investigation, but not because he intended to throw the election to Trump - it's pretty clear from the book that he really dislikes Trump and has no respect for him. My take was that his motive was exactly as he described it - to keep the FBI (and himself) from being accused of having a political motive in its handling of the investigation. Where he screwed up was, ironically, that he thought that if he explained why they were closing the investigation and at the same time criticized Clinton for carelessly handling the emails, nobody could claim he was favoring Clinton. Then, when the letter was released just before the election stating the investigation was being reopened, he was once again trying to avoid seeming political - he thought, like just about everyone else, that Clinton would win, and that if he concealed the new investigation and it later got out, he and the FBI would be accused of deliberately suppressing information that was harmful to Clinton.
The problem, of course, is (1) that he disregarded the FBI's standard procedures for the way it handles the release of information about investigations, and (2) by trying not to politicize the situation he politicized it even more, but completely misread the political climate. The reality he did not see is that even if he had followed the normal procedures and Clinton won, the right wing would have been all over him and the FBI anyhow because that's what they do. But at least he could have relied on having followed the FBI's standard procedures. He could have said (more or less), "We handled this investigation exactly like we handle every other investigation. If you don't like it, tough. Investigate the investigation, and fuck you." Instead, he took it upon himself - honestly, I think, but arrogantly anyhow - to release information while inappropriately commenting on it at first, and then, a few days before the election, notifying Congress about reopening it on account of Humedin's laptop, knowing it would be released in a nanosecond, and in violation of the FBI's usual policy of trying to avoid actions that could influence elections (maybe because he assumed Clinton would win regardless, but still).
So why did he say in his book that he would have done the same thing if he had it to do over? Here's what I suspect: Comey's weak spot is his belief in his own rectitude, his overarching desire to do the right thing. This can be both - or either - noble and/or arrogant. But his actions in regard to the emails have resulted in scathing and deserved criticism. It is at least possible, if not probable, that his actions significantly contributed to Trump's election. So this isn't just a mistake; it's a weapons-grade, world-class, galactic mistake that could even result in WWIII. It's hard for people to admit mistakes, even small ones. It's much harder to admit a huge, horrible mistake, and most people (maybe especially someone who so intensely believes in doing the right thing) will try to justify their huge, horrible mistake. If it's possibly one of the hugest and most horrible mistakes in recent history, are you just going to say, "Hey, I fucked up. Sorry!" Or are you going to tie yourself in knots trying to convince yourself, and especially others, that it wasn't really such a bad mistake and you had a good reason for it?
Maybe some years from now Comey will be able to acknowledge that he really did fuck up, very badly. I do not think he is a dishonest man, but one with a blind spot. Maybe he's trying to atone for his error in some way. In any event, if he can help bring Trump down after possibly having helped to elect him, more power to him.
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