Though I agree that teachers should rather teach how to question things, and therefore should talk about controversial issues, I have to say your holocaust example is a bad example. It simply is not controversial, holocaust did happen.
Actually, what teachers should teach, and I think you agree, would prevent seeing the nonexistence of holocaust as merely a myth rather than the falsehood it is. Teachers should teach that good thinking requires fact checking, coherent thaught and questioning statements. And this is exactly why the Santa-teacher should not have been fired. she questioned an unfounded believe and did so on good grounds and (presumably) with no ill intend (although I guess that these rather abstract lessons might still be too hard on youngsters from primary schools).
