You have to ask if playing on this AAU team will advance his game as much as the alternative at this age. In other words, if he works out with a personal trainer and a personal coach during those 12 hours a week that comprise travel and AAU practice, will he be better off?
I have no idea what place he would be on the AAU team, but if he is a backup guard, then he would be much better served working on his game and strength/conditioning in my opinion.
If he is going to star for this AAU team and they will get him the necessary exposure he needs to get a scholarship, then maybe that tilts the scale. But simply playing for an AAU team guarantees you nothing, especially if you are a backup.
It's hard to imagine that the AAU benefit is worth 8 hours in a car every week for a parent and the kid just for 4 hours of practice.