Homosexual male behavior can cause bleeding, causing an exchange of blood, and possibly HIV among other blood-borne diseases.
Just for the record: I don't believe HIV causes AIDS.
But to your point. It is correct that infections of any type are transmitted quite efficiently by anal sex.
But this effect is not just due to the common occurrence of bleeding in one or both partners. It is simply the nature of the act. The human body offers very little protection from infection with this sort of activity. On the other hand there are natural mechanisms working against infection within the female that do offer such protection.
The result of this is that homosexuals tend to pass infections around like M&M candy simply due to the way they conduct sex. These infections slowly but surely wear down their immune system. Much faster than you and I and normal heterosexual couples.
Then toss in the second most popular activity of the average homosexual, drugs, particularly poppers, and you get another agent attacking their immune system. Slowly but surely they wear out their ability to fight off infections.
And then they die. If they test positive for HIV they have died of AIDS. If not, then they didn't.