I can't remember ever having heard a funny threat.
I think for his tweet to be classified a "threat" there must be some sense of seriousness to it. Threats do not normally start Crap! and finish with 2 exclamation marks. Also, they do not normally get published on social networking sites.
What we have here is a rant, plain and simple. If I was arrested every time I had a rant online I would never be released!!