Agreed. You can't control their "gender" anymore than you can their favourite colours, animals, football teams, pop stars.
But you can control how they're addressed in schools, and critically how other children are expected to interact with them.
In my best friends' school, their two 12 and 15 year old sons have been told there are a few M>F trans, the new gendered IDs must be accepted by everyone, the new "girls" must be addressed as such, any dissent or unfriendliness is transphobia, using the "old" name and gender is out, highest sanctions reserved. Other than that, nada, the kids (and their parents picking up the chaos) will have to work it out for themselves.
Well, guess what? The kids were always known as gay, but there was little homophobic abuse. However now these boys are "girls", the anti gay chants are prevalent, indeed there's quite the undercurrent of homophobia, my friends' boys say it's actually quite toxic, very little of this in evidence previously.
How is any of this helping? The kids reverting to type to apply playground justice when their group instincts are interfered with. The pupils at the centre probably even more unhappy. Reality basically denied by authorities.
And the school/teachers deserve sympathy too. They're just given directives by their trust, local authority, DfE. And a slew of activist propaganda by whatever Stonewall equity group has been foisted in them.