"Dogwhistles" are called that based on real "dog whistles", many of which are pitched too high to be audible to most humans, but are still perfectly audible to dogs.
Rhetorical dogwhistles are things that most people would not be able to identify as bigoted because they're INTENDED to have plausible deniability.
The wording changes are meant to be subtle enough that people really can mix them up accidentally when they don't have much information!
So when the gender critical movement calls trans women "transwomen", they're hoping for 2 things.
this usage will spread enough among people who don't know any better, to give transphobes the plausible deniability of not LOOKING like a frothing bigot constantly.
the usage grammatically places trans women in a different category than other women; it's changing "trans" from an adjective to part of a noun to make this distinction.
The more we can avoid this usage, the less deniability have transmisogynists have when using it, and the less we are helping their cause.
I don't actually think ceding this ground is LESS divisive than pointing it out politely.
