While it's true both sides are being divisive, I suspect Mountain Peaks picked a couple of right-wing names because it's easier to twist RW rhetoric into something negative than it is LW positions.
With just a few words, you can make the Right sound heartless or that they're sucking up to the rich or that they don't care about the environment, and so on. If I were a Russian troll intent on tearing Americans apart, I would do it from the right side, just because it's so much easier (unless it's about gun control; then the left is easier to pick on).
You can pick out the real right-wing people here because they're responses sound sane. Posters like Sylvia Wyss and Obama-Sin-Laden sound like their main purpose is to piss off lefties. And while there are lefties that piss off righties, it's harder to do because lefties say things like, "Save the children or the deer or the rivers." Hard to twist that sort of thing into something negative.