only a 7 day suspension?

After Metta World Peace elbowed James Harden in the head giving him a concussion and 48 hours of pain it's time for worldpeace to suffer with only 7 day suspension and no pay. For those watching the game or looking at the clips after Metta could not pass this on as his way of celebrating. Clearly he knew what he was doing and you know after you hit something you look behind you as a normal reaction to see what you hit and Metta didn't even slighty turn his head. Metta has gone a few seasons with no problems but why the sudden turn around?