Just as a for example, if it was demonstrated conclusively that there was no increase in violence against women as a result of transwoman in female spaces, would you still oppose their presence? I am guessing that you still would.
Because it's not that simple. I have ptsd and amongst other things it's triggered by adam's apples. I don't want them in any space which I consider myself vulnerable for a couple of reasons. A man delivered dc1, I knew he was male but in a panicked moment, seeing his adam's apple from between my legs I lost it. If the student midwife and dh hadn't grabbed a leg each, I would have put a foot through it. Having read my notes before hand and even offered to get a female colleague out of bed, he was totally understanding but I felt rubbish. It's hard enough navigating life avoiding looking between the collar and chin of anyone who presents as male without feeling I have to be on guard everywhere.
That's ignoring the fact that women only swimming sessions saved my life in the aftermath. Turning up with my flatmate, still covered in the marks of his violence and spending time with women (mostly older or from other cultures) who got it without me having to say a word made me feel human again. That perhaps I wasn't as broken or as useless or worthless as I thought I was. Had it been mixed sex or had adam's apples been present at best I would have left, at worse it would have been the final straw.
I've worked with girls who couldn't cope with fully clothed male bodied social workers, policemen and teachers because of what was done to them.
I don't believe everyone with a male body is a threat, I have a son, a husband, I had a father but how can I tell who is? I opened the door to the man who raped me, I'd met him before when he came around to the flat professionally, in the sort of job where your parents tell you trust them (especially when you're white, middle class and Daddy drinks with their bosses) so when he came back a few hours later without his colleague how was I meant to know what he wanted.