Sullivan says it's bad faith:
The bad faith and refusal to be accountable for their own conduct for the last eight years is simply inescapable.
If, by bad faith, Sullivan means conscious intellectual duplicity, then I believe he is mistaken. I suspect, instead, that hard right partisans are simply unable to consciously and rationally process the glaring contradictions between their past and present positions. This isn't a problem exclusive to the right side of the political spectrum. It is a processing difficulty that all partisans share.
In an earlier post, I offered some speculation on why this sort of brain-blindness might occur:
Why might human beings be set up in a way that leaves us brain-blind to unsettling facts about people we like politically?
Perhaps it has something to do with attachment and idealization. An idealizing capacity is intertwined with the ability to form our most intense, beneficial attachments and social alliances. But partial suspension of realism and rationality is required to form and maintain these attachments. We must, to an extent, abandon full objectivity and ignore things that would undermine our attachments. After all, why should parents love their own babies so much more than all other babies? Why should babies and children feel so much more attached to their own parents? And why, indeed, should we fall in love with people who are not necessarily objectively better people than the rest of humanity?
And if the mechanisms that help us to form and maintain beneficial social attachments are in play when we form political loyalties, then it may be that we also have to go a little bit blind to really fall for a political candidate.