Disable app bluetooth streaming?

I have an iPhone 5s with iOS 7, and I like to stream iTunes Radio to my car radio. It works just fine, but whenever I let my son borrow my iPhone for games, the game's audio is also streamed via Bluetooth. I've tried setting the phone to silent, but that didn't help. Turning the volume down on the phone also turned down the music.

I couldn't find a way to disable app streaming on my radio, nor in the iPhone settings. Would Cydia have anything available?