Thank you for the tip. The Greenify solution is a little complicated because it doesn't disable system apps without a 3rd party add on and some extra fiddling. They call it an "experimental" feature, and the app froze when I tried to enable it.
How would one go about making a feature request to Android? This was not a problem until the recent system update, now every time my phone connects to a bluetooth device the music app launches and starts playing. HUGELY ANNOYING!