This whole thing is so muddled now (in the minds of TRAs and many of the public that is) - so that many conversations go like this:
"It isn't safe to have boys in with girls"
"But these "boys" are not boys. They ARE girls."
"They have male bodies."
"That doesn't mean they're boys! How bigoted ARE you? You need to educate yourself!"
"But people with male bodies, however they identify, can get girls pregnant."
"You really are a bigot aren't you. Now you're acting like trans people are all rapists!"
"But my daughter doesn't want to get undressed in front of male-bodied people.."
[see how quickly you have to stop using the word 'boys', for clarity, and to pre-empt the 'but they ARE girls' chant. Language is being successfully redefined...]
"Well, she'll have to get over herself and her bigoted views."
"Look, it's not personal - she wouldn't want to get undressed in front of her dad, her uncle, Prince William.."
"There will be LESBIAN girls in the Guides you know, watching your daughter undress! Do you want them thrown out too?"
"Of course not - they're girls, female.."
"It's INCREDIBLY bigoted to say 'girls are females...' You know what you remind me of? one of those bigots from the old days who used to object to gay people. This is exactly the same!"
The same old arguments come up every time (see the @ GMB twitter thread this morning for example!) and the TRAs seem to think they've triumphantly scored with points such as these... and in a way they have - they obfuscate what is really, really simple - that humans come (largely) in one of two sexual types, and we segregate for privacy and dignity on the grounds of SEX. I should imagine this is confusing to a lot of the public who keep hearing they are BIGOTS if they so much as ask a question around the ideology.