And this was in the context of a political discussion about these very rights, so she was actively trying to influence policy. Some of the "outrage" was exaggarated but you need to keep context in mind: she knowingly picked a side
What JKR said was essentially that she was raped, ergo all transwomen should be held suspect and barred entry from restrooms. Guilty until proven innocent. Nevermind the smokescreen of language and menstruation etc.