I am starting to think about this a little differently. At a minimum, they should not bring him back until the knee is fully healed and all of the impacted muscles around the knee are back in shape. I am not sure where he stands relative to this but Doctors, Trainers, the player, should be able to determine when he is at this point. Once he is fully healed and reconditioned, I would generally say start to play him. There is no reason to wait just to say give it another week or another month to heal. He is either ready to play or he isn't.
But I am starting to wonder if the concern is that the knee is only going to hold up for some limited number of games. That even though he is healed and reconditioned, that there is still some damage or vulnerability to wear and tear. We will be 36 games in at the end of December. That leaves 46 regular season and likely around 25 playoff games. That is likely 81 games. Even with taking off back to backs or whatever, could they be trying to work this by thinking OK, the knee is only going to hold up for 50 games at best so don't start him until regular season game 50 or something (instead of RS game 37). Is that really going to make any difference?
I keep coming back to if he is healed and reconditioned, play him. Be sensible about managing his minutes (no back to backs, etc.) but you got to play him. If his knee doesn't hold up, it doesn't hold up. If you try to limit him to 60 games or 50 games over 80 games, his knee still might not hold up.