I thought Posie was excellent, as always.
Agree that the 'maybe gender stereotypes are good?' pathway they went down was a bit odd. If you teach a little boy 'this is how boys behave' and he realises that he as an individual behaves in a different way, maybe he'll start thinking he must not be a boy, because he doesn't behave like one. I know that when I heard 'girls are X' when I was a child, I just thought it was stupid, because they were only saying it to me because I was clearly a girl and not-X, so they were wrong. Not all children would use that reasoning, though.
Sorry, this is a bit of a tangent, but it's just occurred to me that when most people use these normative stereotype statements, what they mean is ought to. Girls ought to like pink, so if you don't, you're bad at being a girl. Boys ought not to cry, so if you do, you're bad at being a boy. Get better at it. Just plain sexism. But with the is framing, to a literal-minded child, it becomes something else. Girls like pink - so if you don't, you're not a girl? And that would have been a harmless misinterpretation, if somewhat confusing to the child, until the rise of trans ideology.
I did love that she essentially said gender was nonsense, although feminists aren't really to blame for it! They used the word to mean 'sex role stereotypes' which is a useful thing to be able to talk about. The whole 'mysterious ineffable inner identity' thing wasn't a feminist usage, and I am guessing it came about when early TRAs started getting criticised for essentially saying that liking feminine sex role stereotypes made them literally women. Because it's blatantly sexist. An 'identity' obscures that sexism.