Cerek, I would like to add a couple of things.
In my analogy, OK, you have heard him say some threats across the fence, and later you have noticed strange trucks bringing stuff to his house, and that aroused your suspiscions. And if the police said they would come again next Saturday, that is most probably because they haven't collected - yet - all the informations they needed, because maybe some rooms were locked or some of the neighbour's family wasn't there at the time. . So there, in that case, do you wait until Saturday for the trained policemen to do their job, or do you decide to act on your suspiscions ? ...
And in Larry's analogy, it is not any guy who said the guy is bluffing, it is a policeman - that is, a peacekeeping trained officer. Don't you trust a policeman's accuracy and training ?
More generally, in a nowadays society, can a citizen act upon another based on what he perceives as a threat, or must he not handle the matter to the State peacekeeping force ?