Fascinating to see the trans activist response to this.
The obvious, sensible response, would be to agree with JKR. It would be something like: "Clearly, no trans woman would rape a woman. Trans women are marginalised, gentle souls whose only wish is to go peacefully about their lives as women, doing womanly things and using women's toilets. Therefore these male rapists claiming to be women are liars and should not be allowed to claim trans identity."
Instead, they seem to be absolutely adamant that rapists who claim to be trans women really are women. Those of us who refuse to admit that they're women are bad, bad people - hurtful bigots who hate trans people.
Now clearly the reason for this is that they have backed themselves into a corner: once you insist that anyone who claims to be trans is trans, then that has to include rapists too.
But it doesn't do their cause any good, because once you admit that there's a whole bunch of trans women rapists out there, why on earth would women want to allow them into our toilets, changing rooms, hospital wards etc?