Why would we need to reduce the number of homosexual members of our species? So you are basically saying that a monkey is more evolved in it's views and ideology than you are?
I don't think he's saying there's anything wrong with homosexuality from a human perspective. From an evolutionary perspective we generally accept that the 'purpose' of it is to reproduce as much as possible, and clearly having members of your species who don't reproduce wouldn't be helping in that regard.
There could of course be myriad other advantages to having gay members in a population that might outweigh it, and that's sort of what scientists are researching when it comes to homosexuality and evolution. It's not meant to be a judgment that being gay is bad.