By that logic, intersex peoople shouldn't be allowed to have their legal sex binarized either. Oh wait, you won't acknowledge that because it pokes a gaping gash the size of the Mariana Trench in your argument.
Doubt. That's just a regime sanctioned lie to prevent people from changing castes. They don't want men becoming women for the same reason that the Tokugawa Shogunate didn't want Hinin becoming Daimyo.