The period is a result of a natural occurrence: the actual suspension is thirty days. However, it was applied with some time remaining on a prior seven-day trip, and consecutively as opposed to concurrently.
The threat in question was delivered via private message, and is clear enough that, were we inclined to be completely paranoid about them, is actionable at least under American law. I would presume the same of British, Canadian, and Australian law, as well. Probably most, if not all, of Europe. About the only defense for it is a spelling error, and I'd love to see a defense attorney sell that one to a jury.
I am unable to speak to the administration's decision regarding law enforcement, although I can comment that at no time in my ten years at Sciforums have I ever been contacted by authorities in relation to anything anyone ever posted or transmitted at this site.