Reconnect to DAC after disconnecting BT

[Nutul]

(...) is this because the BT connection is potentially two way - ie the user could want to use the Moode player as the recieving device and stream through the 'normal' audio output?

Yes and no...
The thing is that moOde per se is not aware of what you want to do... connecting a speaker / headphones over BT just adds an output device to the ALSA mixer; and you MUST chose it in order to have the audio routed there.