I think it is less to shift discussion and more as a justification in order to avoid responsibility. If we are all evil genocidal imperialists, then it is just a matter of who is the most effective evil genocidal imperialist, not a discussion about genocide or imperialism and how to stop it.
I think it is about avoiding personal responsibility more than it is about a desire to spread propaganda. Alternatively, it might be about showing that ones side is powerful and willing to fight.
If American elections are a sham, then it justifies Russia's sham elections.
If Americans don't get a say in how they are ruled, then Russian citizens don't have to be upset or take responsibility for their own lack of say in how they are ruled.
If America invades Iraq, that justifies China's pending invasion of Taiwan or Russia's invasion of Ukraine.
I kind of knew what that person was doing, and engaged with it in good faith anyway, which I regretted.
The sad part is that when you run into someone like this person, the battlefield is the only way to resolve the dispute.
The battlefield is going to be the arbiter of whether Taiwan is part of china or not too.
These people live in a fundamentally "us vs them" world and frame every problem in terms of a "them." The question is how do we got from "us vs them" to "us vs the problem" or said a different way: justice for all.