I guess the difference between you and me is, I believe a person's past actions is a clear indication of what their future action will be. You apparently believe what a person says he will do in the future, regardless of what his past actions show.
Alright, fine. Let me ask you this, have you seen the youtube video here?
http://www.youtube.com/watch?v=RVBtPIrEleM
What's your take on this?
The link doesn't work. If this is the link that he said he'd run on the Democratic ticket, DUH. Do you know how party endorsements work in NY? You'd be a fool not to have as many as you can, especially in a 5-1 D city, where independents also lean D.
It's worthy of note, that in 1983, Ed Koch had the backing of both the Democratic party and the Republican party in NYC. It didn't make him a Republican any more then this makes Giuliani a Democrat.
To your larger point, a person's past actions do have something to do with their future actions, but it's not the only indicator. If I had judged Ronald Reagan's future by his past, I'd expect that he'd liberalize abortion laws, raise taxes, and generally be a center-right or even Nixon like Republican. Oops. Guess that didn't work out so well.