I take your point, but I'm absolutely all for people identifying any way they like. Man , woman, cat, bird, alien, elf, hobbit, you do you in whatever way that makes you happy and I'll cheer you on.
The limits of your freedom of self expression are when your actions affect other people's rights, equality, access and freedoms of self expression.
The issue is not identification: it's men demanding to control and use women and to own all spaces. That has nothing to do with identification and everything to do with male dominance and sex based inequality, and just bloody awful behaviour. It is absolutely possible to add more and new resources to meet the wishes of self identified elves, hobbits, cats, yada yada while at the same time protecting and insisting on the respect of facilities and provisions for other groups. Answers must work for all: not separate into the givers and the takers, the powerful and the service humans.
I don't care if Starmer has twelve trans kids at home: the issue isn't trans. The issue is not enabling the control and subordination and exclusion of women in law. He ought to be able to get his head around that. Any basically rational person should.