Oh I think I get it – what DJ Grothe meant by saying he thinks “unduly-moralistic scolds end up actively diminishing human flourishing by their sex-negativity.”
He means if we get our way, and sexual harassment at atheist/skeptic conferences becomes unfashionable (aka “politically incorrect”), then there will be less sex at those conferences. There will be less total sex. Our goal, if achieved, would lead to less sex. That equals sex negativity.
Yes, if you define it that way, he’s right. The kind of sex where a dudebro plies a woman with alcohol until she becomes too out of it to consider whether or not she wants to have sex with him and just has it – that kind of sex there would be less of.
So, yes, if you’re thinking about sex purely from the angle of “I want as much of it as possible, under whatever conditions, in whatever circumstances, whatever the other person actually thinks about it” then anything that gets in the way of that goal is going to appear to be sex-negative.
But that’s a slaveowner’s way of thinking about sex.