It's not surprising at all. Newt may be an immoral conservative but he is CONSERVATIVE and can be trusted to govern as a conservative.
Giuliani is a man with a radical liberal record and he is telling conservatives to trust him as he attempts to move to the center and make campaign promises that contradict that record.
Why should conservatives trust a man to keep a campaign promise that contradicts his record if he can't stay faithful to his wife?
And, Giuliani's position on abortion and homosexuality reveal he is completely lacking any sort of concept of morality.
As I've noted before, as the first entrant in the race, Rudy is still lacking a comprehensive platform. From what I've seen in interviews, he isn't turning his back on former positions.