In the sense of population control in a population of a species experiencing overcrowding, bestiality, necrophilia and blow-up dolls, as well as homosexuality, all play "useful" roles in helping to limit overcrowding.

But, the term "useful," as used in this statement (above), doesn't have to have any moralistic connotations assigned to it...as you are apparently trying to do.

My statement is a simply an observation of objective facts.

And I, for one, do not view homosexuality as being immoral.

And there is nothing you can say or do that will change my opinion.

So, you will be wasting your time to believe and act as if you might be able to change my opinion.