I want to be clear that this doesn’t justify Russia’s actions, but the separatist regions of Ukraine have a legitimate grievance. They voted for the prior Ukrainian government (in an election international observers considered free and fair), so they’re justified in seeing the 2014 revolution as anti-democratic.

That's the point. Their guy won the free and fair vote, but people in Kyiv decided he was unacceptable and overthrew him. (There were a lot of extenuating circumstances I'm glossing over, and I tend to agree that he was a bad dude - but if it were a president you voted for, would you be convinced by someone arguing that extenuating circumstances mean it's best to undemocratically toss him out?)