Everyone knew already. The universe does not care straight people exist and it does not care about anyone else either. The only reason humans cared is that homosexuals are less likely to breed and modern cultures have become very obsessed about everyone having kids that can pay the pensions of the previous generation. Homosexuals stop being marginalized when technology exists that makes ones gender and gender preference irrelevant to the ability to create offspring so they can stop being a minority.

This is ultimately same as why women were supposed to stay home raising kids: Any tribe that sent their women and children out to hunt and war did not survive long enough to become a culture. Now we have enough population that it does not risk our extinction so the culture can change.