The logic makes no sense because it specifically fingers Russia, yet any adversary of the United States could conceivably benefit from "sowing division". Once you've left behind the specific support for Trump the underlying logic linking it to Russia collapses but the conclusion has been kept, which indicates motivated reasoning.
There's a deeper issue here too. It paints the posting of political talking points from both sides of a US election as generic "sowing division". That is a world view that is quite totalitarian. I could describe it equally as "invigorating the democratic process by increasing interest in the election" and be no less accurate.
a large part of his support was due to the fear created by the appearance of growing civil unrest
You haven't shown that, you haven't even laid the groundwork for that. It's actually the first time I've ever seen such a claim. Most analyses of why he won point to the weakness of Clinton, his policies in immigration and trade deals, his opposition to political correctness and so on. Not "the appearance of growing civil unrest".
