I think this still undersells the mutative capacity of an institution. You're worried about a fairly obvious abstraction that puts you in their target group. But institutions are living organisms, not evolving logical rulesets and can mutate much more radically.
The organisation is basically training hammers and those hammers will keep looking for nails. This is why means vs ends debates are so central to morality. Humans and organisations are 99% defined by what they do, not why they do it. You might do a terrible what for a good why, but once you achieve your initial goal you'll be looking for other reasons to keep doing the terrible what that you're now an efficient professional at doing.
First they came for the Communists
And I did not speak out
Because I was not a CommunistThen they came for the Socialists
And I did not speak out
Because I was not a SocialistThen they came for the trade unionists
And I did not speak out
Because I was not a trade unionistThen they came for the Jews
And I did not speak out
Because I was not a JewThen they came for me
And there was no one left
To speak out for me
There has long been a poem about Suicidal Majoritarianism, and its history still resounds, but this is not enough. It should be named, and someone should describe its essential pattern:
A cruel logic advises the majority to disenfranchise, exile or kill some minority that it finds burdensome. The majority knows that they can easily dominate this minority, as they are many. Their mistake, the reason this should be treated as a disease even by those who sit in the majority, is that this logic will be applied again to the next minority, continuously, by induction: eventually this cruel logic will be extended to us.
It isn't obvious to the perpetrators of a Violent Unraveling that it is a failure of rationality. A causal decision theorist might reason, "The purges will continue with or without me. It is external to me. My complicity now in this purge does not cause the purges to continue and to expand their scope until my own family is taken by them. I should accept this war of all against all, and strive against the odds to stand as the lone victor" (Perhaps I should try to be less judgemental towards CDT agents. I barely understand them any more.)
I am a logical decision theorist. For me the logic here is much easier to dismiss. I see that the rationale of the purges would abstract beyond their present target. I see that there are ways in which I am a minority, and so one day the logic will apply to me. I decide not to implement the logic, knowing that many other LDT-like agents will stand firmly beside me. Not every person will move with us, but enough will, that the additional safety we gain by denying the cruel logic from our domains shall be worth the blood that we are forgoing.
Culture, writing and enforcing norms, is closer in character to LDT than CDT (though it is perhaps implementable on top of a medium of CDT agents woven into contracts). Cultures can coordinate to prevent a behaviors that are individually rational but harmful when reflected throughout society. Culture did see that few of its hosts would survive Violent Unravelings, and it instated a norm against it.