I understand why they don't want gay/bi men donating blood, as screening blood only to find they can't use it is just a waste of their time
(I'm actually blacklisted from blood drives because something about the makeup of my blood consistently gives a false positive on a test for some virus during their blood screenings; they know I'm totally clean and healthy but they said it's just not worth their time/money/effort to have to go through a long procedure of showing my blood is not infected every time I donate).
But it doesn't make sense to outright refuse organs. The demand for organs (compared to blood) is so high that surely it would be worth the time and effort to make sure the organs are safe? They have to do the tests anyways, since obviously straight men and women can have HIV as well (as can people who have been celibate for a few years... I mean wtf does that solve?

).