I'm not sure I follow your reasoning. Could you explain it to me?
What does it mean that Gulianni supports abortion? Would he want his daughter to get one?
He supports Abortion because as a public office holder he carried out the law. In that regard Bush also supports Abortion. His Justice Dept would prosecute anyone interfering with an abortion clinic.
If you insist that Catholics can not further the practice of abortion then no Catholic can hold public office as long as the right to an abortion is the law of the land.