Sorry... my post should read....
For those (people who believe the bible is mostly to completely reliable), it is impossible to belive Paul to be gay.
As to his ability to be tempted, you are quite right that biblical characters should never be seen a super heroes. However, sinful as He was the chances of homosexual acts is quite low. First because Paul's language in the passages about homosexuality is always from a third person perspective, even though he quite frequently deals with his own sinfulness in an open way. Second, Paul's alleged indiscretions would have ruined him with the Jewish converts and led to his demise much earlier than he died (regardless of the two dates possible).

My original point, flawed as it was in presentation, was that individuals who argue about the sexuality of biblical characters, whether it be Jesus, Paul, David, or whoever, are usually so dramatically different in their definition of inspiration that dialogue is tense, aggravating, and better spent on theories of inspiration or biblical trustworthiness.