[goseminoles]

Yep. In all honesty, I don’t think folks that are HIV+ are lining up to give blood.
They know better(for the most part).
The end result is what counts which is clean blood. No matter the donor.

[fwdude]

It's not just folks who are HIV+ that are prohibited, but also those who have engaged in behavior that is confirmed to spread HIV. Others on this thread have already offered the reason; that there are early stages of infection that are nearly undetectable. There are a host of other diseases that plague those who engage in MSM. Perhaps even some that are as yet unknown.

If anything, the prohibition creates a formal censure of this type of behavior, which tends to have a powerful effect on those who would otherwise like to violate health laws.

If you get the chance and haven't done so, peruse the CDC's website under HIV/AIDS and you might be appalled at the large number of cases attributed to such a small segment of the population. Any sane society would quarantine.