Also, straight people don't get arrested for having sex in a bathroom.
Except when they do.
specific link and
Google link(note that I had to remove the word "homeless" in the search so I wouldn't get that argument and at least one gay story about a them having public sex on a gay cruise (where public sex is likely very acceptable), but they did it while docked in Dominica, which apparently is a no-no)
But as you, I and others noted, gay dudes have a lot more public sex than straight people, so you'd expect there to be more stories on public gay sex than public straight sex. Yes, they have more reason to do it, but that doesn't make it any less wrong.