There are three issues here. First, is what the teacher did legal? Yup. Second, is what the teacher did something a teacher should do? Highly debatable. Third, can a teacher can be fired for using atrocious judgment in the classroom? Probably depends upon the union.I'm betting the teacher gets his job back if he wants it.
Using the best example of free speech -- and a constitutionally protected one at that -- to teach the issue of free speech. Horrors!
And the complaining kid (assuming it was a high school kid) is a complete tool although I respect his First Amendment right to complain.
Could a government teacher be fired for referring to our president by the "n" word? He certainly has the right to do it.
Could a science teacher be fired for claiming global warming is a communist scam? Again, he has the right.
Some things are correct but they ain't right.