Teacher prohibited from calling creationism "superstitious nonsense" in school

This is a very strange case. The NCSE reports:

A teacher's description of creationism as "superstitious nonsense" was ruled to violate the Establishment Clause of the First Amendment by a federal judge in a decision in C. F. et al. v. Capistrano Unified School District et al., issued on May 1, 2009. James Corbett, a twenty-year teacher at Capistrano Valley High School in Mission Viejo, California, was accused by a student, Chad Farnan, of "repeatedly promoting hostility toward Christians in class and advocating 'irreligion over religion' in violation of the First Amendment's establishment clause," according to the Orange County Register (May 1, 2009). "Farnan's lawsuit had cited more than 20 inflammatory statements attributed to Corbett, including 'Conservatives don't want women to avoid pregnancies — that's interfering with God's work' and 'When you pray for divine intervention, you're hoping that the spaghetti monster will help you get what you want.'"

How strange that in the statements listed here that it's the creationism remark that the judge went after. I would think that the remarks to go after would be those that directly insult both the divine being and the people practicing it. Calling God a spaghetti monster and accusing the practitioner of being selfish is a little nastier to my mind than calling a scientifically empty idea "superstitious nonsense." In the spirit of ecumenicism, Corbett probably should have kept his mouth shut or, at most, used some more diplomatic language.

But I'm still confused as to why the judge focused on that one. Any ideas?