Do you mean why other STDs are transfered more by heterosexuals than homosexuals?
No, not at all. You appear to have set up a moral rule equating statistical correlation regarding the transmission of a virus (or any STD) to a measure of "harm" and so "wrongness" of an activity.
But type of sexual act is only one variable in which one can find correlation. Thus we could find that "urban sex" is more correlated to STD transmission than "rural sex", or "black sex" than "white sex". Indeed those might have significantly greater correlations than "homosexual sex" as compared to "heterosexual sex".
Do you remain consistent and label all correlatives, or just one chosen group that you want to single out in an apriori manner?
One could even look at the specifics of sex act. It may be found that homosexual oral sex, or homosexual masturbatory sex is less correlated to STD transmission than hetero-vaginal or anal sex. Does that make the former wholly homosexual acts less harmful and so more right then the hetero sexual acts?
You see I am gauging consistency of this moral formula. It seems to me if we are simply judging homo vs hetero acts in general, then it is an ad hoc formula designed to try and slam one group using temporary and selective criteria.
holmes
"...what a fool believes he sees, no wise man has the power to reason away.."(D. Bros)
"Don't believe I'm taken in by stories I have heard, I just read the Daily News and swear by every word.."(Steely Dan)