Segregation of everyone who is biologically difficult.
This is totally illogical and incorrect! And no one is 'segregating' anyone except by sex. As examples posted above show, not everyone who would be (non)-segregated would be 'biologically' anything, let alone 'difficult'.
So, we have two spaces segregated by sex (just plain ole biology). For those whose appearance in the correctly-sexed space causes inconvenience/risk/confusion (transmen, butch dykes, drag queens, intersex, blokes in dresses, drag queens, effeminate gay men in full-on swish mode), or just anyone who doesn't want to use multi-person single-sex facilities for any and no particular reason, there is the alternative of (single-cubicle) 'gender-neutral', unisex, any and everyone able-bodied spaces.
Which gives everyone a choice!
Who knows my missus might even like to use it when the constant re-iteration of 'Oi mate, that's not the gents' gets to be too irksome.........
It's only the wilfull neglect and erasure of all these other groups and none that makes it look like transwomen choosing not to use the ladies (cos they pass so amazingly well you know), would automatically out these wonderfully-passing persons as transwomen.
If it's a space anyone can use it's not segregation. And for the sexed spaces, as long as (unlike my place of work, much grrrhhhhh
) there are equal numbers of cubicles for each sex, then there is no sex discrimination either. After all, given that some trans activists argue for all gender neutral facilities, how can the choice to use them be segregation? The only 'segregation' here is enforcing single-sex spaces, which then lets you see why some trans activists really, really want to get rid of these as well!