The guy is trolling threads, trust pages, and has alluded to violence. Of course he should be banned. Why is that even a question? Mods should take some action.
You know, as well as I do, that trolling cases are quite difficult here and are often not handled (in a sense that action is actually taken against the user).
That already exists, and it is called the ignore button:
You won't see any content from him, unless someone quotes his posts. Though I'd expect people to know this.