Party loyalty thing. He'd be a total outcast if he didn't give a rousing speech, and after all, he's Bill Clinton, he can lie for a solid hour with no hesitation or remorse. I really have no doubt he's pulling the lever for Romney on election day, but he can't publicly stab Obamussolini in the back now and have any friends left in the Popular Democratic People's Front to help with anything he or Hillary might want later. I too am not sure Hitlery is still going to be interested come 2016, but it's still possible.