Try going into Restrictions and disabling Connect.
I wouldn't really suggest that going into iOS 9. iOS 9 has removed that option and if you had it disabled prior to install you lose the ability to bring it back.
Also it might be something else draining his battery (or he is moving around lots within the app while playing music) I've had Music app literally use 0% over the course of a 45-50 minute train ride. (Started the ride with 96% and ended the ride with 96%) Music playing the whole time, screen off (only turned on screen twice to quickly check email.) This was also with everything on but all locally store music with some downloaded for offline AM music.