Probably - the point is to declare Syria to be Russia's ballpark, and to deny it to Israel/US. It's a diplomatic signal that the Russians won't tolerate Israeli hands in Syria.
Perhaps, though I think its as much about not abandoning allies / friends as it is trying to prevent regime change, or rather prevent a cack-handled attempt at regime change that does nothing apart from kill a load of innocent people, destabilize the country for at least a generation and further strengthen the Salafis and their valiant attempt to wind the clock back fourteen hundred years.
Also how mad is it that the Russians have a saner foriegn policy than the UK, US and France? That hasnt happened in ages.