That's it exactly.
We're "all women together", until we're not.
So transwomen's fear of violence from men in bathrooms is legitimate, while women's fear is hysterical.
Biology isn't related to gender AT ALL, unless it's about some non-replicable neuro imaging study that totally shows the ladybrain.
Feminism must include transwomen, because we are all women, exactly the same, but we must not talk about issues like female genital mutilation, because that excludes transwomen.
A transwoman may comment on what it is like to be a woman, but a woman may not comment on what it is like to be a transwoman.