The problem with the article is that it confuses morality with preference. The dead chicken example sets up this confusion right from the beginning: Of course it's not "immoral", in the sense of being anyone else's business to have a say in, if someone wants to fuck a dead chicken before eating it. Are most people likely to find the idea disgusting and not want to do it? Yes, of course that, too. But there is no contradiction between these two things, because it's not the purpose of morality (in a modern liberal democracy, at least, as opposed to a theocracy) to stop other people doing things you happen to find disgusting.
Similarly, the fact that casual sex between consenting adults is morally neutral is not complicated and really doesn't require so many words. The idea that cultural developments which prioritise casual sex over slowly developing pre-sexual relationships have been bad overall for women is a really interesting and important one that should be talked about, but doesn't negate that moral neutrality.
And this:
O’Neill is correctly identifying a problem — the fact that horny and unscrupulous men (“fuckboys” in contemporary slang) will regularly manipulate naive women into casual sex that leaves the women feeling wretched. Such sex isn’t illegal, since the women do say “yes”, but it’s unpleasant and unkind.
is really simple. Lying is wrong - that's hardly a revolutionary moral discovery. Lying to get people to do things that are against their own best interests, because they probably wouldn't do them in posession of the truth, is particularly wrong.