I was baffled at that comment too. iOS should pause playback on headphone disconnection (wired or otherwise) as well. My only guess would be some sort of rogue app that doesn't respond to OS notifications, so it continues to play sound even after disconnection. In that case the OS would obligingly send the audio stream to the default device (ie. on device speakers). That said the default apps (eg. music or podcasts) should be fine.