Metaphor...if I may.
I don't really have a dog in this hunt; I've been following along more or less just to have something to read. I can see valid points on both sides of this debate -- if one were to say there were only two-- but on a more fundamental level, what I think is going on is this:
For years and decades and centuries past, "gender" was strictly defined as a stark, binary, black OR white box to check off, even though it isn't, wasn't, and never has been, but...that's the way you grew up with it and that's the way you're used to it being. And the world is changing faster than you're prepared to accept. That isn't an indictment of you; it's simply to say that (in my opinion) what you're doing is refusing to get on board with this emergent re-imagining, this burgeoning acceptance, of gender as being more fluid, more malleable, only because it flies in the face of the way you've always known gender and are used to thinking of it.
Do you allow for that possibility?
I would suggest that part of the problem is the forced redefinition of a term to fit a political narrative.
Roles, presentations, and expected behaviors based on sex have existed throughout time and throughout cultures. Some of the behaviors are actually sex-linked, and show a degree of persistence and consistency across eras and nations. At a bare minimum, hormones affect behavior.
The rest of it, however, has been socially determined, and shows considerable variation past and present, and from region to region and group to group. The clothing and ornamentation that are expected to be worn by either males or females is entirely socially defined. Color associations, social roles and jobs, and a lot of behavioral aspects are socially defined and imposed.
Up until the 1950s, gender meant exactly the same thing as sex. It was simply the polite term for biological sex, used to distinguish the biological element from the act of intercourse. Then Money came along and redefined gender as something separated from sex so that he could justify doing sick sexual experiments on children. That was followed up by Butler, the Mega-Queen of meaningless babble, who pretty much made gender something completely devoid of any understanding and turned it into something people could don or drop at will.
Currently, "gender" is being forcibly and coercively redefined to represent a woo-laden internal soul that can have a sex the opposite of ones body... or even have a sex that is not found anywhere in nature and doesn't exist. It is simultaneously. however, being used to represent the set of sex-based stereotypes that are bundled up into social roles and behaviors. All of which, at the end of the day, robs it of value for discussion and understanding.
It's become a meaningless term... and that meaningless term is being foisted into publicly policy to override the very real and objective fact of sex.