I'm wondering if they can stabilize the ankle with some sort of brace that he can play with? It seems he's not really feeling any pain and can walk normally. I think a lot will come down to whether or not the risk of further damage is too great or not, but also, how effective he would even be if he can tough it out.
Yes, they can try to do that. The question will be how much can it be stabilized externally, given the loads that athletes, especially pro basketball players, put on their ankle, to the point where a) there's no pain; b) there's no (significant) deterioration in performance; and c) there's no risk of dislocation or other tendon damage.
If this had happened to one of us, we would be walking around not worrying about it, probably wouldn't even realize we had it. Eventually the tear would heal on its own. But obviously we don't put our ankles and joints under the types of stresses that an athlete would

I have a feeling that they might see if he can give it a go tonight, see how he feels and see if he can handle things. Because the only way he will know is to try it out. If he can't perform to the required standard then he'll know pretty quickly just from the movement. But the medical staff have to make a detrermination as to the risk of aggravation, and he's a pretty fragile fella.