Depends on how you look at it when you look at it.
In times of overpopulation, homosexuality could be seen as a constructive adaptation, not detrimental to a species' survival.
And, in response to your second comment, a certain percent of homosexuality in many species is in fact normal.
http://www.livescience.com/animals/0...y-animals.html
In any event, this planet's ecosystem would be much better off with fewer humans, rather than the go-for-broke baby-making policies common to so many 3rd world nations. That's where homosexuality is clearly a good thing. Some countries take a dim view of gay sex, and nations such as China prefer to punish both heterosexual couples who have more than one child as well as gay couples who have no children at all. Other countries practice female infanticide, with the result that over time, there are many more adult males than adult females for coupling, yet homosexuality is banned.
Ya, from a purely evolutionary point of view, I'd say that human's inclination to overpopulate this planet, overconsume its resources, and overpollute its lands and oceans, will sooner or later result in uncomfortable circumstances. But since humans can't find ways to control reproduction, as a species, we'll end up f***ing ourselves to death.