Mental purity

Glenn Reynolds has it exactly right.  The zero-tolerance approach even to tiny gun-like objects that no one could possibly mistake for a real gun has less to do with physical safety than with the extirpation of dangerous concepts from the minds of children.  Of course it doesn't matter whether the "gun" is an inch long or made of Poptart or formed with a thumb and fingers.  All that matters is the idea.  Soon the word itself will be taboo, if it isn't already.  They'd punish the thought itself if they could read minds.

Children will have to be taught that guns do exist, and are not inherently evil, but that the people who run their schools are incapable of remaining calm if the concept of a "gun" enters their heads, and therefore must be protected from the very thought.  (But cross-dressing and Che Guevara?  Totally OK.)  They can then draw their own conclusions about the value of the other ideas they are receiving from these people every school day.