Bear with me for a moment.
( @Ekphrasis said something interesting on another thread about what closes ears to what we're saying and I've been thinking about closed ears more generally.)
Would it work better to sidestep the whole "Transwomen are women" mantra instead of taking it on?
Just talk about "natal women" having different needs to "transwomen". Every single time.
Because I think "no they're not" stops the brainwashed from listening.