This shouldn't be a philosophical question of who's a "real woman". Which is more likely: a transwoman getting harassed in a men's restroom, or ciswomen getting harassed by transwomen in theirs? Need you really ask?
Also, in general, it's ok if you don't have opinions about this. If you can't identify with the struggle, consider yourselves lucky. But don't make yourselves part of the problem my discriminating, generalizing, or insulting ppl.
All these arguments are simply smokescreens (which IronAngel also already said) to derail the struggle for basic human rights into a blame-game and putting marginalized groups in indefensible positions.