However I see a lot of complaining about this problem on the official SyncMyRide forums about this, even with the latest Sync update.
I am still messing with the settings to see if I can preevent this. I have ot set to off but it still starts playing anyway. I have the same problem with PlayerPro, except it has an option to NOT start auto playing when a BT headset is connected.
If I wanted my hardware and software to boss how I use my phone around, I would've bought an Apple product. Someone suggested using an app called Headset Blocker, but it appears that when I receive a phone call, it doesn't stop Pocket Casts, so I've got to hunt around for where I'd left off.
I Googled and found a TWO-YEARS RUNNING thread on the Android Bug Tracking site complaining about this issue on just about every phone. I can't see anywhere in the app or in the phone's BT settings to disable it.