How do any of those sources know that she was mistaken for a man? What if she changed her mind half way walking into the bathroom or on her way out? Or 'his' way or 'their' way?
I am asking seriously how we are determining it being mistaken or not. I know this can sound transphobic but this is actually about law/policy and enforcing protections of both cisgender and transgender people if we are to do so since you are giving a cisgender person misgendered, how do we know for sure that the people telling her to get out were mistakenly calling her a him/he?
I ask you sincerely to specify to me how we know a mistake was made, should we look perhaps to social media beforehand, ask relatives which gender pronouns this individual went by beforehand or what?
I'd say in this case a solid basis for it being mistaken is that it is a genuine female adult who happens to appear masculine. Would you agree that is the case? Would you also agree that if nobody who was male-sex entered a female bathroom/washroom that the hostility and caution the cis females had around her wouldn't have taken place nearly as likely as they'd have given the benefit of the doubt since people don't do that?
I am also curious if you support the solution of unisex bathrooms in most places, the issue of 'protecting women from men' is kind of negated due to transgendered people existing so the 'safe space' from adult males is kind of becoming moot, I also think unisex bathrooms/washrooms would be a huge step in evading the clash altogether with respects to that.