"From her own words, I take Rowling’s position to be that the sex one is assigned at birth is the primary and determinative factor of one’s gender, regardless of one’s gender identity—a position that I categorically reject. The science is clear and conclusive: Sex is not binary."
Eh? That doesn't make sense even by tra standards.
She appears to be saying that your sex doesn't determine whether you're masculine or feminine. Which is completely true. But then goes on to say that whether you are masculine or feminine, is determined by your sex, because sex isn't defined as being male or female.
You just need to get one of these people in a room with a microphone and ask them a couple of questions - and tell them they're not allowed to storm out when the corner they've painted themselves in to becomes suffocating.