The thing is, they give relevant examples. - IMO a child shouldn’t be put in isolation for wearing the opposite sex uniform. Kids should be able t9 wear whatever uniform they want. The problem is when they say a boy wearing a skirt is a girl, entitled to use the girls’ facilities and the girls are bigots if they object.
I don't think kids should be put in isolation for anything really, but I am not so sure this business of uniforms is as straightforward as is often thought.
Uniforms that differ according to sex are a cultural tradition obviously, rather than some innate connection. But by the same token, clothes are just clothes. Beyond functionality, does it really matter if some kids want skirts and some pants, any more than if some kids would prefer blue to green? It's really just a personal preference, which isn't a big factor with regard to uniforms.
But putting so much weight on the preference for traditional girls vs boys clothing, I think we've fed into the idea that there is something special about our preferences in those things that is separate from sex but somehow just about cultural traditions around sex. It's played into the idea of essential gender identity separate from sex.