You're wrong, not all his comments are about russia (it took me about a minute to randomly search through his comments and notice a comment about GTA, and I think that's all it takes to prove you wrong: not all his comments are about russia if at least one isn't).

Why are most of his comments about russia (if that's the true even): perhaps he is interested in the subject and has a nice attitude of only speaking about something he is knowledgeable in. Or maybe the subject of russia is something he find very emotional and feels an urge to speak about it.

Let me mimic your rhetoric:

Why are all your comments about russia, always pro-russian?

Are you spreading propaganda because you're on a payroll?

From their postings they don't sound like a troll account, and is definitely irresponsible of you to assert that "ALL of their comments" are about Russia when it only takes about 60 seconds to determine otherwise. If they talk about Russia a lot, it's because pro-Russian propaganda is very pervasive, also here on HN -- and unpacking and responding to every instance of it can almost turn into a full-time job.

That said, they (mopsi) do seem to like to say some rather weird, and also intellectually dishonest things -- such their assertion that it was primarily the Russians, not the Germans (with the help of local collaborators) who arranged for the extermination of Baltic Jewry in the summer of 1941:

https://news.ycombinator.com/item?id=39141260

Despite all evidence to the contrary.