If there wasn't really a trans panic there wouldn't be passive aggressive comments like that and the harrassment that follows to start with.

Making it "only 2 sexes lol" is bad faith, incorrect semantics, or just bad branding to frame it that way. Semantics aside, what it's really about is that some people feel psychologically different than their biological gender. If you frame it that way, there's no reasonable option other than to give them freedom and acceptance. Hence, "only 2 sexes lol" and other distractions like "won't someone think of the children".

I'm not trans so I don't understand it from personal experience, but it's not in my nature to write off surprising or counterintuitive behaviors as wrong.