Perhaps, yes. But I >think< that power to the OBD port keeps SYNC alive and does not affect the servos or electro-mechanicals that control trans operations. I could be wrong on that and more research would be necessary before I'd consider a 4 down tow, but that is how I understand it. With the battery disconnected the drive train system intelligence is non-functioning and therefore a 4 wheel freewheeling tow is safe, but the minder would keep all the SYNC settings.
Maybe someone who is better versed on this can provide a better explanation. As I said, I think that's how it operates but I could be wrong.