I dunno, with a hit like that, you can have all kinds of problems that do not show up right away. My head injured clients over the years have convinced me that all of the damage from those type of hits are not always discernable right after the initial injury.
Brain injuries are funny things. You can get knocked out and bounce back rather quickly, or not even lose consciousness and die from a slow bleed. That bad luck of hitting his own guy's knee on the way down could easily have rendered him paralyzed, and may still have given him brain damage with short term memory loss and an inability to perform a list of tasks (sequencing) or even (like my neighbor hit on the head with a tree limb her husband trimmed) dwelling on single thoughts (perseveration).
I do not think that the status of his injury is even remotely conclusive at this time.
Had it been a shoulder separation, I might agree with you OC, but the Natasha Richardson death should remind us that any brain injury (and a concussion is a brain injury) is a serious deal. I will gladly lose a couple of games if it prevents putting Tim back in too soon.