Wow, this is so inappropriate.
I don’t care what your personal opinion is, Rob: you didn’t need to share it here, nor in such a hurtful way.
Even if we both agreed that the author was in thrall to some bizarre, delusional cultural moment, and thus prone to be upset by imaginary or immaterial issues, I’d view your “response" as a basic violation of good manners — which, on the 'Net, pretty much = deliberate trolling. Your tone lacks the self-conscious unpleasantness of the usual troll, which is one reason I’m responding to it. (If in fact you were deliberately trolling, I’d find your response a lot more intelligible.)
Troll or not, I feel confident I can assume you don’t know the writer. Given that, you’re not involved in her/their pronoun anxieties.
So, what’s it to you — and really, this is the crucial question — what she/they worries about? How does it improve your life to slam her/them for a concern that’s absolutely irrelevant to your existence? Do her/their worries about what her/their friends say when she/they isn’t around harm you? If so, how do you expect your nasty response to help protect you from such harm?
I’d be fascinated by your responses to these questions — though I don’t expect you’ll share them.