Well... then.... giving Russia "carte blanche" in Syria wouldn't be a good idea. Right?
We have no strategic interests in Syria. Assad is Putin's bitch. His preservation is to their benefit. An ISIS theocracy is not.
Why wouldn't we let the Russkies do what they need to to prop up their client state? It serves both our interests. Ours, because we have none there except eradicating ISIS and bleeding Hezbollah and the zeal for a Caliphate.
We have already given Russia too much wiggle room in the Middle East. They (along with Iran) are the unstablizing force, IMO. Sure, we can't exactly stop them without a full-on (probably nuclear) war. But acting as if they were actually doing something positive in the region is foolhardy and wrong.... and more of the same stupidity. Just sayin....
Iran and Turkey are going to be a much bigger problem for the world in the future. The Arabs to the South already know and see this. We cannot undo decades of stupidity there, especially the irreversible damage Obama and Hillary wrought and the stupid tidily winks played with the Palestinians and the Israelis.