The Russian purpose certainly wasn’t to reform Ukraine for the benefit of the Ukrainians.
But even so, giving your argument the benefit of the doubt (which I doubt you are making sincerely), we come back to St Thomas, and the “just war”.
I’m totally sincere and my point of view is shaped by the belief that we are in a worldwide war to dismantle the cartel that has run it for 100 years. Putin has his part to play, Trump has his part and likely in the end we will discover Xi had his part to play. That last part remains to be seen.