Good for them! Bravo. How brilliant to stand up to this thuggery, although I daresay that the Mail on Sunday had a thing or two to say about this!!
I still think there's a massive bone of contention here around the definition of 'biological sex'. A narrow interpretation limits this to XX vs XY and penis vs vagina. As we know, there is so much more to biology than that. From alleles, to myriad hormones, from brain signals, to glands. There are multiple bodily functions that defy narrowly-conceived reductionism.
And yet we have ceded this ground with barely a whimper. This reductionist approach to biology was always the peg on which the TERFs would hang their hats and it's an area that is increasingly worth our while unravelling.
Aside from that, how on earth are they going to police their definition? If you defy them and state that you were born a biological woman with XX chromosomes, how exactly are they going to disprove it on the spot? I accept that it's harder if you are pre-op, but if you're a post-op female I don't see what they are going to do to prove you aren't what you say you are.*
I think all of us who have transitioned or who aren't transitioning can make a biological case otherwise, why would we put ourselves through this? The TERFs of course rant that it's because all MtF's are closet abusers, which is an argument that ought to be driven out of all quarters.
(As it happens I have a chromosome mutation and there are a number of members on this forum who have various varieties of intersex natal status. What of us in this dystopian country?)