It is not a statement designed to convince. It is designed as supporting evidence for a certain mental model, yes, but to a degree that's pretty hard to appreciate unless you've spent some time with this mindset, they are not operating in a world where one person says an argument, and the other person evaluates it critically and decides whether to accept or reject it.
Their model is that if a person in authority says an argument, people "under" that person's authority are obligated to accept it. To evaluate for yourself whether the thing the big NYPD sergeant is firmly telling you is terrorist propaganda, is actually terrorist propaganda or not, is already a subversive act that may be punished by harsh criticism and humiliation at least, and possibly a total expulsion from the social circle or threats to your physical safety.
It's not a good model, but it's the one they operate under, and it works for them as individuals for the most part. So that's what they run with.