I believe the Western values are what makes it an effective tactic, and it's the same reason why they're calling the Ukrainians Nazis while simultaneously running towards fascism: if you say that X is a Nazi and is committing genocide, you'll have a visceral reaction in the West that creates sympathies/doubts of other narratives in at least part of the population (this will not work the same way/to the same degree in non-Western societies). If the West was fascist, I'm sure Russia wouldn't be talking internationally about Nazis and genocide because it wouldn't have any impact.

You're very right about the historical narrative as an internal component. Connecting current conflicts to WW2 will make people fall in line much more quickly than saying "it's about natural resources that were mistakenly buried on the wrong side of the border and also we want a land connection to Crimea". Much like Americans will always invoke freedom because it's part of their national identity and people are less likely to question why they're invading Iraq if you mention it. Russia being threatened by fascist forces in the West is a continuation of the existing historical narrative and neatly ties into it.

It's definitely a much better PR strategy than Germany had in Afghanistan during Operation Enduring Freedom where our secretary of defense prominently said that Germany's security was being defended at the hindu kush. It's makes sense in abstraction ("we need to confront those who disregard human rights even if they're 5000 km away") but it's not concrete and it didn't increase support for the war at all.