I find this whole story bothersome. Usually I feel pretty confident about leaning toward allowing as much speech as possible but I feel pretty uncomfortable with the speech this guy engaged in. It's certainly fine to say that you think the world would be a better place if a particular person were dead, but to give home addresses, maps of buildings and photographs of the peoples faces is pretty dark. At some point it becomes incitement to murder which seems wrong. I'd think it would be pretty easy to allow and disallow the criminalization of this type of speech as a function of ones bias, it's a blurry line and bias is probably the only nudge that is needed to push most people from one side or the other (myself included).
Unfortunately, this is one of those places where a clear line probably cannot be defined. I think the majority opinion is convincing. Reading his words, it's pretty clear that he wanted someone to kill those judges, and was inciting someone to do it. Unfortunately, with laws like this, in the wrong circumstances saying "I wish [official] was dead", might be enough for a judge.