To those saying they would be perfectly happy if trans men used women's spaces, I'm not sure that bears scrutiny. Trans men often pass more readily than trans women. Women are highly alert to men in women's spaces. Trans men are treated with hostility in women's spaces from fairly early in transition, and women don't hold back if they read someone as male in the ladies loos.
Yes, I actually agree with this. Especially the post about a trans man with penoplasty. I don't think being trans makes you the desired sex, but if you go through a physical transition, it does make you something different to your birth sex. This is why I think specific trans spaces are needed. A trans man with a beard, no breasts, on a high dose of testosterone and with a surgically constructed penis would conceivably cause discomfort to women sharing the same space. Nor from that person's point of view is it in their interests to share space with female bodies because it would breach their dignity. Ditto for trans women. They are not biologically female, but if they have undergone physical transition, it's not really appropriate to ask them to share with natal men either. Everyone has always worked from the assumption that there can only be provision for 2 genders, but once we get rid of that assumption, it is possible to meet the needs of natal men, natal women and trans people.