Rationality has nothing to do with that particular question. I think it's largely about the unwashed masses having a morbid fear that maybe queerness is contagious. And thus we *must* keep the blood supply pure of tainted drag queen blood.

But apparently turning the entire female population bi would be just hunky-dory with the Powers That Be. :-D

*sigh* That "had sex with a gay man" question took me off the blood-donor list, too.