GrannyMacawell
It matters because safeguarding is based on sex not gender. toilets, prisons, women refuges etc should be based on sex. let's not confuse sex and gender.
If a boy wears a dress is he a girl. or is he a boy in a dress?
I think the nuance missing is that the danger, or perceived threat, tends to be from cis males when we discuss safeguarding on sex.
Transwomen, non-binary, and gender fluid people are incredibly vulnerable in terms of being victims of violence. Throwing them into a population of cis males b/c of their assignment at birth is like throwing an injured lamb among the wolves. Do they not deserve any protection?
As to your question, that depends on how they view themselves, doesn't it?
I'm not interested in policing someone else's identity. And since clothes don't have genitals, they're neither male nor female by any definition, so I'd simply say they were someone wearing a dress.
Frankly, Billy Porter looks absolutely fantastic in a ballgown.