Can't Disparage Religion in California Schools

I admit, this ruling surprises me:

A federal judge ruled that a public high school history teacher violated the First Amendment when he called creationism "superstitious nonsense" during a classroom lecture.

U.S. District Judge James Selna ruled Friday in a lawsuit student Chad Farnan filed in 2007, alleging that teacher James Corbett violated the establishment clause of the First Amendment by making repeated comments in class that were hostile to Christian beliefs.

The lawsuit cited more than 20 statements made by Corbett during one day of class, which Farnan recorded, to support allegations of a broader teaching method that "favors irreligion over religion" and made Christian students feel uncomfortable.

During the course of the litigation, the judge found that most of the statements cited in the court papers did not violate the First Amendment because they did not refer directly to religion or were appropriate in the context of the classroom lecture.

But Selna ruled Friday that one comment, where Corbett referred to creationism as "religious, superstitious nonsense," did violate Farnan's constitutional rights...

The establishment clause of the First Amendment prohibits the government from making any law establishing religion. The clause has been interpreted by U.S. courts to also prohibit government employees from displaying religious hostility.

I'm not saying that it's acceptable behavior for the man to disparage people's religious beliefs, but I definitely cannot view his actions as a violation of the Establishment Clause.

Update: a much more academic commentary can be found here.

Yet how does this play out in other situations? Here's an example: When I taught criminal law one year, one of the hypotheticals involves the question whether casting a voodoo spell on someone, believing that it would cause the person to die, should count as a criminally punishable attempted murder. That's a difficult question; as I noted before, a few court opinions have considered it and quickly concluded that it shouldn't so count, but as a doctrinal matter it's not clear why -- generally speaking, trying to kill someone is attempted murder even if the attempt is clearly doomed to failure, for instance because you think your gun works but it's actually broken, or because you use a substance that you think is poison but really isn't. Why not if you use a method (voodoo) that you think works but actually doesn't?
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A couple of students after class actually told me that they thought this might be offensive to people who believe in voodoo, but my view was that I can't teach my classes with an eye towards not offending people who believe in voodoo, just as I don't have to worry about people who believe in ghosts or werewolves or unicorns. But under the court's reasoning, would I have been violating the Establishment Clause?
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But the result is either that (1) teachers can't condemn voodoo, astrology, young-Earthism, and so on as the bunk that they are, (2) courts have to draw lines between which religious beliefs may be disapproved of and which may not be, or (3) teachers are even more at see about what they are constitutionally barred from saying than we've seen from past endorsement cases.

Like I said, a much more academic commentary.