McCain did the same thing in Waco on Monday night. The man mentioned that he thought Cindy would make a much better looking First Lady than Bill. Of course the audience loved it and McCain used the same response regarding not attacking his opponents. It was weak.
I think it’s because he thinks he can win over “independent minded Democrats” with this type of behavior and he knows conservatives really are stuck with him, and won’t vote against him. He can alienate them all he wants and still feel safe that a majority of them will turn out to vote for him, seeing him as the lesser of two evils. He knows he doesn’t have to court them. Of course that’s just my armchair analysis. :)