I think the idea is gender is not sex. It's a weird concept as first and took me 4ever to understand what on earth these guys were on abt.
I haven't come around to accepting the solution some have proposed of legally recognizing multiple genders since my understanding is that what they're referring to cannot actually be limited to that (31) or any specific number. It could potentially be as varied as there are are individuals on earth. Sounds like voo doo, I know, but it's essentially a different balance of the masculine/feminine instincts in each person (we each have both) as I've personally come to conceive of it. I personally believe they come from the hunter and gatherer instincts. You could have a thoroughly hetero bio woman who is hyper masculine and a thoroughly hetero bio man who is hyper feminine and any kind of combination in between.
The best solution I see is to let people present themselves in the way they feel comfortable without calcifying it. It could be exploratory. I have no beef with that. If someone presents themselves as a woman to me, I'll treat them as such regardless of their chromosomes. What I have an issue with are people who maintain the presentation of a different gender with a set social cast and then demand to be treated as the opposite gender. If you present yourself as a woman, you shouldn't seek to punish people who treat you as such. That's placing too great a burden on society. On the other hand, if someone reasonably presents themselves as one gender, they should be treated that way IMO. After all, we don't go around testing pple's DNA or checking their genitals to discover who/what they are. We rely on social signifiers of gender. So treat people according to this social 'language', whatever their chromosomes/genitals. That's my view. If I meet a person I can clearly see is biologically male but they dresses like a female, has a female name etc, I won't go out of my way to treat them like a dude like insisting on using masculine pronouns, for example. I might slip but it'd be a mistake, not deliberate.