What you are actually making is something like a “lesser of two evils” argument or some bet on tradeoffs paying off that one party may buy and another may not. Having explored the reasoning this far, I would suggest this is one class of circumstances where even if you beamed all the facts into two people’s minds, who both had “Average” morality, this is one of the situations where there would still tend to be disagreement. This definitely doesn’t hinge on someone wanting something bad, like genocide, for the disagreement. People could both want the same outcomes and diverge in their conclusions with the facts beamed into their minds in this class of situations (which, to my original argument, differs tremendously from physics).
I hadn’t seen old man Chomsky talk about Ukraine prior to your video above. I think though, if you look at his best work, you might be able to softly mollify the impact, but it’s not like he’s pulling his ideas about, say, every single US action in South America and the Middle East being very bad for the people they claimed to help, out of some highly skewed view. Those border on fairly obvious, at any rate, and your video’s recasting him as a “voice of moral outrage” hinges on his off-the cuff interviews, not his heavily cited work (as I mentioned The Chomsky Reader, which is a different man than the one in the video)
Even setting him aside as a reference, looking at the recent history of US war, at the most generous, considering Russian badness and US badness, any “moral high-ground” argument for the US being good in this case will boil down to a lesser-of-two-evils assessment. Also looking at US history, you lose some of the “this is just an annexation” because US proxy war since 2014 would fit the pattern of pretty much everything the USA has done both recently and for the past 100 years.
Your point about also looking at Putin/Russia is fine, and it should be considered as well as practical solutions to the matter. I think we all would call Putin a criminal, this isn’t a question at hand. The question is if another US adventure, this time in Europe, is actually going to turn out all that well, or if Russia as a failed state will turn out well for Ukraine or Europe, or if this will turn Nuclear if you refuse to cede any ground, or if the Russia/China alliance will break or not, or for how long the US can even afford and support more wars, etc, etc. These are mostly practical matters that are indeterminate and make the intervention questionable. In practical senses, they present different good/bad tradeoffs and better/worse odds bets on outcomes to different parties that amount to weighing different “lesser evil” projections in the outcome. They don’t hinge on our moral intuitions differing at all.
(And again, all this differs in category and the way it behaves from Physics)
Then let’s say we broadly agree on the morality of the matter. The question still remains if another US adventure, this time in Europe, is actually going to turn out all that well (as most haven’t for the people they claimed to be helping). We also have to wonder if Russia as a failed state will turn out well for Ukraine or Europe, or if this will turn Nuclear if US/NATO refuse to cede any ground, or if the Russia/China alliance will break or not, or for how long the US can even afford and support more wars, etc, etc.
On the other side, do we worry if we’re being Neville Chamberlain because we think every aggressor will behave as Hitler in 1938 if we give an inch, so “We gotta do something?” There may even be merit to the sentiment, but “We gotta do something” is one of the most likely ways to screw any situation up. Also, given the US’s history of interventions, setting aside morality, just looking at the history of outcomes, the response is questionable. Looking down the road, if this conflict or anything else significantly weakens the US, economically, in domestic politics, or leads to an overextended military, then Ukraine might be lost all the way to the Polish border, not just the Eastern regions.
These are mostly practical considerations that are indeterminate and make the US intervention questionable without even looking at the morality. Given perfect knowledge, you would have a probability and risk management problem on your hands, which often fails to result in a clear convergence of positions. And going back to my original claims, this makes this type of thing very different to Physics and Chemistry and their extensions.
EDIT: Perhaps the most important question comes down to this: Russia clearly screwed up their risk management (as your message alludes to). How can US/NATO do far better with Risk Management? Maybe even better than they’ve done in all their wars and interventions in recent history?