more on plan "b"

This is from the WSWS. So, the question remains, why would the Russians agree to(and even be a party to the initiation of) this ceasefire agreement? On the other hand, perhaps those that say the agreement will be interpreted properly, that is in a way that permits the Russians and Syrians to continue the air campaign (and even ground campaign) against certain specified groups within Syria if those groups insist on continuing the fight, are correct. I would tend to doubt it though.