This is patently outrageous. A kid is claiming he follows the Flying Spaghetti Monster religion and that his religion requires him to wear a pirate suit. He was suspended for being disruptive.
Outrageous. We'll assume, for the sake of argument, he does genuinely hold the belief (in my mind, believing in a spaghetti monster in the sky is no more or less rational than believing in a mad jealous god who smites people if they don't believe in him, or in a guy being born from a virgin and coming back to life and ascending into heaven and turning wine into blood (I like my wine as it is, thank you very much)). Anyway, I digress.
I'm sure the religious wackos would come down against this guy, agreeing that yes, his costume was disruptive.
The problem is, they come down on exactly the opposite side when it comes to mad Christians being disruptive. For example, they're strange bedfellows with the kid in the Bong Hits for Jesus case (recall that the kid, outside the school, had a poster saying that jesus likes pot or something similar and was suspended for being disruptive). They're on his side, because they want to be able to put up signs outside schools saying "Jesus thinks that being gay is bad" or "don't kill your foetus." They also routinely intervene in cases where kids wear t-shirts that say "the Bible says homosexuality is bad."
Of course, this is somewhat apples and nectarines. If the kid truly believes his religion and that it requires a certain dress, he should be allowed it. That's like a nutjob Christian needing to wear a crucifix (a macabre ornament if there ever were one).
That's entierly different from allowing a kid to be disruptive by saying "because of my religion, I believe that homosexuals are evil, and I should be allowed to say so." That's disruptive and not required by the religion.
Similarly, if the kid walked around saying "Arrrrrrrrrrr me hearties!" I'd be all for suspending him too.