Parenti's "non-falsifiable orthodoxy" statement explains it. It really is just reflexive, deeply ingrained, and completely unexamined anti-communism. It's not a real event to most of them, it's an article of religious faith that proves the righteousness of their anti-communist beliefs. Trying to tell them "no one died in the square, about 300 people including unarmed pla soldiers died in fighting between the pla and insurgents several blocks away" is like telling someone that the tears leaking from the virgin mary are a rusted out sewer pipe. You're not revealing the truth, or educating them. You're attacking their religious convictions that form part of the foundation of how their world works, and they react accordingly by shutting down and denying.

All of that type of propaganda carries with it a note that "they did it to their own people!". There is in implicit understanding (or was, at least, when I was growing up in the US) that it is natural for militaries to kill people from other countries, a group which also conveniently includes minorities. Imo this was probably a deliberately crafted piece of cold war propaganda, since the US never really had to kill white people to suppress unrest.

You know it