You’re kind of missing the point.

I’m making fun of them by pointing out how they’re wrong

It’s an easily falsifiable statement.

Yes

It’s an incendiary statement designed to foment division.

Yes

Everyone knows there are more than 2 genders.

Actually no, not everyone knows. You’d be surprised how people are ignorant to these matters (by choice, or repressive environment)

There are only two genders…

Except for: <giant list of genetic, epigenetic, developmental, etc… things that happen with human beings>.

Not to mention all the other things that happen with other living things