As you stated, it is difficult for non-Russian readers to come to any conclusion because of the number of posts he is making in that board instead of the global board. Having said that he seems to be wearing a mixer campaign earning $10 per post therefore financial motives are definitely important to him (regardless of who is controlling the account).
This seems tricky to prove. Since most of us probably don't speak Russian natively, we can't personally evaluate if his style of communication has shifted. The best course would be having members who previously interacted with him closely, either on or off the forum, confirm or deny perceivable changes. However one detail gives me pause - if financial motives were important, why stop participating in the signature campaign?