I feel that lifting weights could be counter productive in some ways for basket ball.
You need speed, agility and explosiveness in basket ball.
While weight lifting will help with strength and explosiveness it can also cause mobility issues due to almost everyone's lack of stretching.
While a young person may benefit from weight lifting if they are lacking strength, in this case I think sports specific training would be more beneficial.
Of course if he wants to lift then just keep him safe and keep it light.
Just my 2c. You're his dad so you know where he's at.