Agreed about the IP banning, but it's not quite as dangerous as they make out. There is the risk that banning a single IP address may affect a couple of other users, which is why it should be avoided, but in some cases it may be the best option.
That's a decision for the admins and moderators, though, and not for me, so I'll leave you to it now :)
The guy posting this stuff seems like a whack job. I don't know if he'd go as far as to actually attempt physical harm. Most of the "internet tough guys" I've ever talked to seem like the type who would cry if you confronted them in person. Either way, this dude's message is disrespectful, slanderous, a verbal attack, and an implied threat of physical harm. I think our friendly neighborhood TA admins have every right to get rid of this trash as soon as they catch it.