Dude your theory about the fuel sliding to one side is so wrong. Its under pressure, not going to happen, especially when doing a 180, its not like the throttle would be wide open to use all the pressure. I usually bs around in my car, I do it in the rain in the parking lot and my car never shuts off. Your friends car is probably shutting off because he leaves it in gear while he does it. Its kinda like locking your brakes while in gear, by the time you come to a complete stop with the wheels locked, your car should be shut off.
Dani I would believe that the car is shutting off b/c of your auto drive train. Its probably a safety feature like someone stated earlier to protect the drive train. Your front wheels would end up going reverse while its in drive.