In his e-mail, he is telling parents if their children are harassed to call the police to investigate. The threat of a lawsuit would stop the gossip in its tracks.
I absolutely agree with the principal on this. Asking parents to watch their children and keep them from “social networking” isn’t something that he should even HAVE to do. These kids aren’t old enough to have good judgment and shouldn’t be using cellphones or iPhones to go on networking sites.