Teachers employed by the government are assigned a curriculum. That curriculum is not speech. The teachers are acting as government trainers and are not engaging in speech. Any free speech done by a bureaucrat is to be done outside of the bureaucracy, otherwise they are speaking on behalf of the state. And the state has no innate right to speak at all. Let alone freely.

This is the heart of the matter. Public schools are state bureaucracies and curricula are dictated from the top down. Individual teachers can be degenerate pedophile child molesters on their own time and, since we aren't about to dismantle US public schools anytime soon, the sooner we get rid of the types of "teachers" who exhibit themselves on TikTok the better off everyone will be.