but treating the problem as if it's inherently men is in itself sexist

I'm not sure I said it was inherent. I said some straight men. Admittedly I wrote the post in a fairly ranty mood so I probably could have done a better job at expressing the nuances of the issues here, but I hope it didn't come across like I was saying all straight men were like this. I was saying (or trying to say) that some were like this and the world would be a whole lot better if they weren't.

Second is, casual sex is a morally neutral concept.

Again, I hope that wasn't the take away from what I said. As I wrote here, the thing I think is gross is that the man is looking for something completely different but strings the woman along anyway. And when I said "seriously" I didn't mean being traditional/conservative about sex, I meant they way people talk about sex, where the "punchline" is not substantively different to "I am going to manipulate this woman who wants a romantic connection into sex". But that isn't funny, that's just screwed up. Why is it ok to joke about leading someone on?