I agree the objection to children viewing the art is absurd, and ironic given the nature of the school.
However, the episode I think isn’t primarily about opinions on art at all, but rather that is a proxy issue for the broader question of whether the state gets to say what constitutes a good education, or at least the minimum bar of what type of education a child has a right to as a member of the society, or whether the parents have the say.
Because the school made a technical mistake, even if it’s of no consequence, it creates an opportunity to assert the point as a matter of principle (and therefore as a matter of principal).
This may be similar to this:
Therefore, what people (like me) tend to think of as eye roll backwards prudishness is really not an issue about the sculpture at all, that’s just the stand-in (is there a phrase for that, a fake thing to argue over just to exercise the argument?) for enabling the real point, which is a reminder (or assertion of the claim) that the parents (or right wing parents, or conservative parents) are in charge. The parental complaint is sort of the social equivalent of flying an air rights assertion flight in international waters.
The reason there was a fuss in Florida isn’t over the art. It’s routine for the art to be shown. The fuss is because the teacher neglected to get permission from parents. That was an minor oversight, but it was used as a chance to exercise muscle over the technicality, because the principal was seen as more significant than the triviality of the transgression considered unto itself. If you violate my airspace by 100 meters, it maybe of no material consequence in and of itself, but my nation state may kill you over it.
That’s what happened when the senator inadvertently violated a rule by being on government property when he made a statement on television he made many times before but from a short distance away, and then realizing the error self-reported the mistake. The violation may not be material but it’s important in the eyes of the ethics committee to exercise its prerogative.