What's your take on censoring childrens' costumes in public school Halloween parades?

The front page of Friday’s New York Times featured a story on measures taken by public school administrations to prohibit weapons (real and fake ones), masks, even costumes deemed “too scary—or offensive, gross, or saddening” in Halloween-related activities at public schools. (The story can be found here: http://www.nytimes.com/2009/10/30/us/30costume.html) The author writes that many schools encourage “positive costumes” like animals or food items, some even going so far as to send letters to that effect to students’ homes. Perhaps most intriguing is that the administrators quoted in the piece are representatives of California school districts, primarily in the Los Angeles area, which has its conservative pockets but is overwhelmingly liberal.

I’m torn on this issue. While I’ve always felt that public schools tend to overdo it with respect to restricting student activity (my elementary and middle schools were quick to ban “distracting” toys as they cycled through their popularity, from Beanie Babies to chatter rings), even play-fighting with toy weapons is potentially injurious, and the rules governing acceptable behavior in public schools have never been subject to “real world” protections from censorship. Still, mandating that costumes, “not depict gangs or horror characters, or be scary” seems excessive.
What do you think?