How does that work in practice? When I am at my local supermarket on a Saturday morning and need to pee, there is no good reason to exclude me from the female lavatories. At the other end of the spectrum, while I look female, I sound male as I have done little to alter my speaking voice, as it is something I rely on in my job as a barrister. I quite accept that I should not be the volunteer on the phone taking the first-contact calls at a centre dealing with domestic violence against women.
That's great, and I respect that RMW has enough self-awareness to say that.
The difficulty of self-ID is that it opens the door to people with less self-awareness, or who simply do not care about the distress they might cause, to answer those phonecalls. Or for predatory men to do so for the kicks.
The need for single sex accommodations isn't to protect vulnerable women from those who have the self-awareness and self-restraint to recognise that somewhere isn't for them. It's to protect them from those who seek to take advantage.
I accept that most transwomen are not in the latter category. The difficulty with unrestricted self-ID is how do you weed out the predators.
If there's a need to exclude some men, then the regretful conclusion is that it must be necessary to exclude all men, because the bad apples don't go around with a badge saying so.