The answer is no damage whatsoever as I expect the power circuit is not used in the audio connection or is turned off based on the USB specifications.Just noticed (after couple of hours) I had plugged in the charger to the audio micro-usb port, can it potentially damage the Mojo 2 or there is some built in protection to mitigate such scenarios.
Think of it this way, if you plug your laptop into that socket to listen to music from the laptop, the USB cable carries charging power and the audio signal and that’s the designed usage for the device. All will be well or they would have said don’t plug into laptops, which would be an odd thing because that’s a very common use case.