It's interesting .. we've seen a few stories like this in the last year, haven't we? Jessi Slaughter and Rebecca Black come to mind. It's like we haven't collectively established the appropriate response for a child being super annoying on the internet.
I agree that it's badwrong to troll kids, especially threaten them with violence. I also think that regardless of age, when you post something controversial on the net, you should be prepared for the fallout. (please do not read that as excusing people for being rude to kids) People were real jerks to Jessi Slaughter, but on the other side of the coin, she also shouldn't have told anonymous that she was going to "pop a glock in your mouth and make a brain slushee." This is why I wish there was a course in elementary schools about how to use the Internet and how to relate to the Internet.
@Nigel: I did not say we shouldn't criticize or condemn people