I am not worried about Tatum integrating with the team in time for the playoffs. There is enough time to work though that. And I am assuming that if he does come back, that he will have demonstrated that his conditioning is in place to be near his 100% self. Now touch and feel, at NBA game speed, may take some time to get back, but again, he just needs to have it back in time for the playoffs.
So my logic is that if the conditioning is not in place, he won't come back. If he does come back, it will only be if he has absolutely demonstrated that his body is ready for the NBA from pretty much day one. The rest (touch, speed of the game, etc.) will take some time, but he will have some time.
Said another way, I see it as one extreme or the other. Either he doesn't come back, or he does come back and he plays at his normal self. I don't see him or the team wanting him on the floor, especially in the playoffs, if has limited minutes or limited recovery. No reason to do that. What would be the point?