What's the difference between rationalising something and insisting on treating it in its historical and political economic context?

I note as an aside that almost every time someone puts the Ukraine war into context, a lib will claim that this must be (uncritical) support for Russia/Putin. But one doesn't necessarily follow the other. (I'm giving libs the benefit of the doubt here, as I don't think most know the difference between critical and uncritical support.)

How does one add nuance if those who've already come to a conclusion reject the nuance as rationalisation (apologia?) for leading to a revised conclusion.