Correction - it isn't a motion detector, it's a compass. I went back out and secured my jammed in wire better and moved the radio around to see if I'd get the message. Well, I didn't get the message but when I put it on the map, the vehicle direction changed as I moved the radio.
I jammed the wire 'properly' (if that makes any sense) and went for a short drive. Compass still works, no lockout message.
For anyone that wants to jam a wire in instead of moving the mute, look at the front of the wire harness (the side that plugs into the head unit) and you should be able to see the wire al