What it means is context is pivotal in understating what is said. Your mind numbing reasoning would treat innocuous statements, containing a hyperbolic threat, as a five alarm fire. A friend tweets about another friend in a group tweet, “Someone should send a hit squad to John’s house for tweeting the ending of the movie and spoiling it for us.” Or the phrase, “If you tell me how the movie ends before I see it, I promise I’ll kill you.”
Here’s a concept, not all threat are the same, not all threats are equal, not all threats are actual threats, not all calls for violence mean actually to engage in violence. Hyperbole, exaggeration, jokingly, an emotional outburst, etcetera, which involve some threat, aren’t threats as they are hyperbole, joking, exaggeration, mouthing off, etcetera.
The fact your argument cannot distinguish between the differences of statments containing threats, specifically those which aren’t threatening from those which are, plagues your view. It is irrational to lump all all statments containing a threat into one boat.