I think it would be a bad political move to turn Assad over to the Jihadists. He was an ally that let the Ruskies stay in Syria. If the Ruskies pull the rug from under him Russia may have difficulty getting other nations to trust them when they ask for bases/ports in their country. Turning over political allies to an enemy is bad business.
I agree with you. Also, the new leader only controls a portion of the forces and his control is not as absolute as it would be in a Western nation. Enough people in his forces and the other players hate the Russians that the Russians would never be safe. Claiming x attacked the Russians is a recruiting and fund raising tool for x.