He played really well today and there's no reason to think he was "finished" and utter bullshift like that.
He is most definitely a much better defender compared to Lenglet, so I see no reason not to get his post back the soonest.
Alas, injuries are part of the game, and none of us actually have a clue if his knee wasn't fine. Anyway recently he had a broken toe which is common, heals without reminiscence and I've seen dozens of great players returning from even more serious injuries, and even playing much better than before after a considerably long gap.