The school claims rights and privileges under valid state law, and the federal judge simply tosses the case out.
Now, let's go at this from a different direction. Let's suppose the family becomes aware of what the school is planning to do and then accuses the teacher of "misinterpreting" the syllabus and claims he or she is nothing more than a pedophile cruising for sex with kids.
Since this is an allegation of a crime the parents should be fairly immune from any sort of legal retribution, but the teacher is definitely on the spot. Even if he or she finds support from the school administrators, the teacher is going to be seeing his or her career prospects evaporating.
In today's environment of female teachers engaging in multiple sex acts with groups of young male students, seems to me this would be the best course of action. You might not get everything you want, but other teachers would be loathe to follow the party-line all that closely in the future.
"Since this is an allegation of a crime the parents should be fairly immune from any sort of legal retribution..."
Yeah -- until they are busted for making false allegations. How would that be a righteous thing to do -- and why do you think someone could get away with that so easily?