Here in Cardiff we already have a problem with inappropriate behaviour in the Village swimming mixed changing facitilites:
BBC NEWS | Wales | Concern over pool sex complaints
We know that predatory men go to extraordinary lengths to access their girls and women (boys/men too, of course), gaining employment in child-related work-places, befriending families in order to be close to children, targeting vulnerable women for abusive relationships, and so on.
Who is to say that some predatory men will not use self-ID to access women and girls? That's what we're opposed to. We aren't and never have been, anti-trans people. Never. Those of us who go back to the 70s and 80s in our fight for equality, and who achieved much for later generations, have always shown solidarity to trans ppl. The accusations of transphobia are tedious and tiring.