Any attempt to determine McCain's true motives is necessarily pure speculation. It's possible that McCain has convinced himself to actually believe the lies he has been telling. But here's a more likely explanation: All this dishonesty can be understood not as a betrayal of McCain's sense of honor but, in an odd way, as a fulfillment of it.
McCain's deep investment in his own honor can drive him to do honorable things, but it can also allow him to believe that anything he does must be honorable. Thus the moralistic, crusading tone McCain brings to almost every cause he joins. In 2000 and afterward, McCain came to despise George W. Bush and Karl Rove. During his more recent primary campaign, McCain thought the same of front-runner Mitt Romney. Not surprisingly, Romney was the target of McCain's most unfair primary attack--an inaccurate claim that he favored a withdrawal timetable in Iraq.
The pattern here is perfectly clear. McCain has contempt for anybody who stands between him and the presidency. McCain views himself as the ultimate patriot. He loves his country so much that he cannot let it fall into the hands of an unworthy rival. (They all turn out to be unworthy.) Viewed in this way, doing whatever it takes to win is not an act of selfishness but an act of patriotism. McCain tells lies every day and authorizes lying on his behalf, and he probably knows it. But I would guess--and, again, guessing is all we can do--that in his mind he is acting honorably. As he might put it, there is a bigger truth out there.
This is a quasi-justification? I thought it was a straightforward attempt to explain, rather than justify, McCain's thinking. (Keep in mind that this passage comes after a lengthy, detailed recounting of McCain's compulsively dishonest campaign.) Granted, I don't have any sentences like "McCain is a bad man," but I thought the part cited by Lemieux would strike any sentient reader as a portrait of a man who had completely lost his moral bearings in the pursuit of power. Does Lemieux see the Star Wars movies as an attempt to justify the actions of poor Darth Vader, who only wanted to save his family?