I was a conscientious objector to Red Cross for a long time. I still hold the view that their questions target sexual orientation, rather than sexual practice.
As a female, you can have unprotected sex with a different guy every night and pass their screening, as long as you have no reason to believe those guys have done anything with another guy.
On the flipside, two guys can be in a long term committed relationship and not be allowed to donate.
I give blood now, but I still object to the form of the questions.
In a similar vein (tee hee) I can't give blood because I lived in the UK in the 80s and they worry about mad cow disease.
Yet I was a vegetarian the entire time. I guess they are managing risk at the population level and I'm in a relatively small group so they don't have a rule for me.