Metis M entered service 1992. It has been used in Lebanon by Hezbollah against Merkava's. Russia denied having provided the missiles to Hezbollah. Likely route woud have been delivery to Syria and then smuggled to Hezbollah. Which is what the Israeli's initially claimed.
So, it is used by Syrian government forces. It has also been used by Free Syrian Army. Initially, Metis missiles originated from looted Syrian army depots, while later external suppliers could have been involved. It was confirmed, for example, that Bulgaria have sold 6 sets of 9K115-2 Metis via USA to Syrian Rebels.
So, imho, its a little premature to fully pin this on the Russians.
Map with 9K115-2 operators in blue