Can a constitutional provision violate itself?

That's what my mom, Ann Althouse, suggests, based on this thought-provoking post by Eugene Volokh about this case, in which the federal district court for the Central District of California held that a public school teacher violated the Establishment Clause by referring to creationism as "religious, superstitious nonsense" in front of his class.

I recommend reading Volokh's whole post, but here's the crux:

The court may have been quite right as a matter of existing doctrine, and if we are going to say that public institutions can't advocate in favor of creationism, it makes sense for the doctrine -- which has been defended by claims of symmetry, such as that the government may neither endorse nor disapprove of religion, may neither advance nor inhibit religion, and may neither show favoritism nor hostility -- to also bar statements that creationism is superstitious nonsense. 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 [sic] about what they are constitutionally barred from saying than we've seen from past endorsement cases.