Given that JKR's position is that humans can't change sex, Lia Thomas shouldn't be swimming in women's swimming competitions, male rapists shouldn't be housed in women's prisons, we shouldn't be performing irreversible medical interventions on gender non conforming children and calling women menstruators is gross, I think you'd have to be really fucking stupid to disagree with that, let alone say it out loud.
And lol at the idea that rising to the top of the Labour party is a sign of intelligence. The world of politics is like a toilet in which shit floats to the top. It would be much harder to reach the top as an intelligent person.