A lot of people do not draw the distinction between talking about things in an educational context versus it being a way they express themselves for their own needs. Laws like this make people afraid to do so until it is contested because the act of contesting it is itself punitive. The cooling effect is implicit in the design of the law because it recognizes law removes people's ability to support themselves in a society before it has a chance to be tested meaning only the secure of a minority under extreme fire can contest it and that means becoming very visible in circumstances where one's safety often relies on being invisible.

This teacher is likely under extreme fire right now by a mob of people telling them they are a pedophile, delusional, harmful and trying to exploit every shred of exposed weaknesses to gendered nonsense one naturally lets be known when one comes out as non-binary.

Where legal protections are shaky schools will fire teachers under concerns for that teacher's physical and mental safety if enough parents are valued at being a threat by feeling empowered by their interpretation of the law or the idea that a school is operating outside the law. Ultimately running a school is government money that needs to be paid so an employee going up against a school board for wrongful dismissal will not impact the individual school as much when the main currency for the school board employees is time and complexity of a bunch of individual parents suing because their little darling asked them what someone calling themselves Mx. means when they came home.

That's a good point. Gorsuch's surprising cross over to rule with the liberal justices in a recent supreme court ruling (Bostock vs Clayton County) allowed gender and sexual identifies to be protected by current federal employment law. The very logical conclusion that comes from, any discrimination on the basis of sexual or gender identity revolves around a person' s assigned sex at birth, which is definitely prohibited, and you can't discriminate on those things without it being an illegal discrimination test based on sex. Basically if you fire someone assigned male at birth for wearing a dress but not someone assigned female at birth for wearing a dress, this is sex discrimination, already protected by current federal law. Similarly if you're firing a male for marrying a male but not firing a female for marrying a male, than that's sex discrimination already prohibited by current law.

Unfortunately I don't know if the current Supreme Court reasoning would extend the existing federal law to protect non binary honorifics, since the school could argue it would fire anyone using a non binary honorific regardless of that person's assigned sex at birth. Though maybe if you could get the school to admit they'd allow a non binary honorific for an intersex individual that would open up the door for non binary protections too via current law? But this is why we need a real updated federal law explicity protecting against discrimination on the basis of sexual and gender identifies, including non binary identities. In the meantime the states that do have explicit protections in their state laws are going to be much better places for non cis and hetero people to work in.