I don't think they're actually right wing trolls, just because I don't think I've ever once seen one of them accidentally "break character" so to speak (at least, I'd bet that they do largely believe what they claim to believe, I don't think tankies really are as left wing as they think they are, but that's a whole other discussion). I suspect it's more that they're a community that exists on their own site because other more mainstream sites wouldn't take them, so they're going to both be an echo chamber and one that self-selects for extremes, and given the small size of lemmy they suddenly find themselves being a big fish in a small pond.
I do still support defederation with them though, I don't think all their users are tankies, but I've seen a fair few that have been making the kinds of points those types tend to, mostly apologists for the Russian government. It does feel kind of unfortunate for those users that aren't, but if a significant quantity of trolls are coming from one instance, to the point of being able to overwhelm communities on another instance, then defederation is the best tool other instances have on a network like Lemmy, given the designed lack of any central administration to appeal to.