Not necessarily, some species(penguins, I think) have evolved to produce some gay offspring to help raise other offspring. It can in fact be a survival gene, while the homosexuals may not procreate themselves, the female may have evolved to have both, and it may help survival of the species in question.
What I'm saying is, just because A + B doesn't OBVIOUSLY answer C, doesn't mean it's simply illogical.
"I mean, if ever I saw a trait that evolution would suppress, this would be it."
I'd study more on genetics, evolution, and development, as well as anthropology before simply jumping to conclusions.