I would like to think - occasional idealist that I am - that TW or TM could have the empathy and understanding for those whose sex class stereotypes they wish to adopt to not colonise their sex-specific spaces. Particularly TW with regard to female spaces; TW are men, and men pose a statistically significant risk to women. In addition, a notable proportion of TW (potentially the majority, at least in the cohort aged 30+) are not suffering from gender dysphoria but are autogynophiles: men with a sexual kink for being seen as a woman. Men who get erections when they colonise women's spaces and call it "gender euphoria".
Dress how you want, call yourself whatever you want, take whatever hormones and have whatever body modification surgery (as an adult) you want. But when your kink, or your mental distress, leads to you to demand other people play along with your self-image in a way that denies their own reality, affects their rights or transgresses into their spaces...well that's where the line is drawn. You can believe whatever you want about yourself; you can't force other people to indulge you in that belief.
And for whoever it was who thinks this is a sign of feminism "regressing"...WTF is progressive about telling young boys they must be girls if they prefer to play with dolls and like the colour pink? Did the 1980s never happen? Children as young as 3 and 4 have been referred to the Tavistock clinic as being "gender dysphoric", put on a pathway that leads to puberty blockers, cross-sex hormones and surgery, made lifelong patients and it is based entirely on stereotypes.
Also, a final note in case this is something people aren't aware of: when considering discrimination under the protected characteristic of gender reassignment within the Equality Act, the comparator for a transwoman is a man who has not undergone gender reassignment. Treating a transwoman like a man is not discrimination.