Well, the funny bit is that those old guys were still flexible enough to change their minds when a suitable framing of the thing was presented to them, by which point they recognized it all as the more generic scenario of "aggressor attacking victim to take their shit" and made their opinions based on what their principles were on that kind of thing.

I would say the problem here was tribalism: they were predisposed to believe, support and excuse the aggressor because they felt, due to long ago experiences and indoctrination that "they're our people". Fortunatelly these specific people were open minded and intelligent enough to be able to step out of that and consider the whole thing from a detached point of view.

Plenty of tribalists are pretty much religious fanatics when it comes to all those "acquired truths" and the truthfulness, trustworthiness and wisdom of whatever the tribe's leaders say.

IMHO, tribalist is by far the greatest problem, though I would agree that it and inflexibility are deeply connected.