Unfortunately for all those up in arms about this, this is a safety issue. If they don't like the policy, pull out of the school district. If my kids got harassing phone calls from other students, the school is going to hear about it. Even if it's not during school hours. The fact that when at school, they're compelled to be in places where they may have to encounter someone who's made a credible threat against them.
It doesn't change because it's on the Internet. Doesn't matter if it's a phone call, a letter, Facebook/Twitter/Tumblr/WhatsApp/etc, skywriting...
If the kids have nothing to hide, then release it. If not, pull the kids from the school. They're not obligated to go, and they're certainly not obligated to be abusive assholes either. We don't need more enabling of bullying and peer enforced sociopathy.
Doing absolutely nothing and being hands off isn't making things better. If you don't think this is a problem or worth tackling, I don't think you're hooked up right. I don't know if this is the right approach, but I'm not hearing any better ideas.