I think this is more complicated than that. A true “sour grapes” wouldn’t be so transparent. No one believes he actually thinks she is ugly, and no one serious could believe anyone would actually be fooled by this, so we can only conclude that the intention is not really to convince anyone that he thinks she is ugly. Instead, he is pretending to pretend he thinks she is ugly. Why? Consider what we actually take from this Tweet: He does not think she is ugly, he thinks she is attractive and he would like to Be With her, and is upset that he can’t. Since this is so obviously inferred from the post, we must assume that such a reading is the point. In fact, he derives some satisfaction from the mere statement of his sexual desire. This seems odd, but on consideration, it’s obvious that men must derive some satisfaction from making their sexual desire legible, since they do it so often.

Why not state it plainly then? Pay attention! The incels never admit sexual attraction directly, except perhaps with regards to celebrities or AI generated women designed to be “perfect.” Either way not “real women” in an important sense. I will return to this point later.

We saw that the incel, far from denying his sexual attraction, actually affirms it here, saying “she is beautiful and I wish I could Be With her.” More interesting still is her part in this game. She is also not speaking plainly here. No “Chad” has ever called her a “Stacy.” That is incel jargon. Normal people don't use it so frankly. Again we must conclude that the information we most readily take away from the statement is what the statement actually intends to say. What we take away is that: 1. She is aware of the incels talking about her, since she can parrot their jargon 2. She is aware that they are lying about finding her ugly. She thus invents the fictional Chad and uses him as a totem with which to talk about her feelings regarding the incels’ attractions to her, which she plainly perceives. The message is “I know you’re lying about finding me ugly. You think I’m beautiful and you wish you could Be With me.”

But this is not mockery; she expresses how the sexual interest of the (fictional!) Chad is bolstering her self-esteem against the apparent insults of the incels. But since the Chad is not real - merely a displacement of the incels’ sexual attraction - and since we have seen that she must understand that the incels do not really mean their insults, we must conclude that she really intends to communicate her feelings about the incels’ affections. That is, she is telling the incels, as directly as she dare, that she has received their message, and appreciates it. She is a young woman. and like most young women, she is terribly concerned with being attractive, and gains satisfaction from being told she is attractive.

So we can see, buried underneath three layers of irony, that the real conversation is as follows: He:”””You are beautiful, I wish I could Be With you””” to which She:”””I got your message. Thank you”””.

And now we return again to the previously dropped question: Why wrap this in so much misdirection? Why not flirt more explicitly? With the woman’s perspective now considered, we can answer this more satisfactorily. Were this exchange more explicit it would carry its own implication:that the flirtation should or could or might be consummated. This implication is frightening to both of them, but of course especially to the woman, who, in truth, may not want to Be With the incel, who, frankly, is probably not attractive. She likely also still views Sex in general with some trepidation. Nonetheless, she appreciates being found attractive, even by men she is not actually interested in. Knowing this, they initiate this game of irony, in which each can get the satisfaction they want without the risk that comes in making things explicit.