Who knows, this seller might have lost interest with his Russian coin collection or inherited it and didn't want it and hence selling it to finance his other collections. Sounds perfectly reasonable to me if that is the case. Afterall now is a good time to sell Russian coins. (as well as bad time for me to buy

)
Rarity wise, Uzedenikov didn't mention it as rare or such. If I was going to counterfeit a profitable ruble, I would be counterfeiting a Peter III ruble.
Indeed, I do see some issues with the wear on the ruble, but again that will not stop people from bidding to some insane levels. At this current moment, it's already over 100 dollars. I am not too willing to gamble on such though, unless it was from a dealer that I know well enough.