I'd recommend reading mcherm's comment again. He doesn't state that 90% could be pranks. He states "If, for instance, I were to learn that 90% ..." This is called "reductio ad absurdum", and is a pretty standard method of arguments. The statement from x86_64Ubuntu was that a report of violence in all cases is responded to by a SWAT team, with the implication that this is correct and reasonable behavior in all circumstances.

From my reading, mcherm is giving a hypothetical scenario in which the automatic response of sending a SWAT team would be unreasonable. The conclusion isn't that we exist in that hypothetical scenario, but that more information is needed in order to determine whether and how close we may be to it.