Kate,
This is not a political issue, a matter of homophobia or political correctness.

If a girl has sex with a bunch of guys that are all straight then her risk is minimized compared to having sex with a lot of gay dudes.
Why?
Check the CDC and get the information.
The fact is that straight guys are among the lowest percentage for hiv. Right down there almost with lesbians.
Gay guys on the other hand are in a really high percentage.

Lets say you have 2 groups of 100. Group A is very prone to having colds, let's say 20% have colds at any given time while group B is not and only 1% has colds at any given time. Now if a girl went around and fucked all 100 guys in either group, which group is riskier for her to fuck?
It's not hard Kate. It's cold...but that's reality.