McCain, the narcissist, is focused on his legacy. He wants to be more than just a footnote in the history books (I.e the white male who lost the election of 2008 to the first black president). He knows progressive academics will write the history books. He has likely bought into the concept that conservatism is dead and demographics mean Barack Obama and the Democrats will be successful in transforming the US into a socialist state. By helping further the progressive agenda (immigration, gun control) he is hoping future historians will herald him as a visionary who helped bring about the transformation and tried to temper the racists and fascists in his party.
Of course in the present his behavior ensures he will continue to be the star Republican on the Sunday talk shows.
In other words, McNutt has stretched his 15 minutes into a half hour.