I was expecting WOT to jump in here, but this info is in other threads.
The cable cut point in the trunk does more than disconnect the 12V battery, it includes an extra wire and disables all 12V circuitry including the air bags and opens all main battery contactors..
It is a bad idea to pull the battery disconnect under the cup holder until after you do the cable cut. It causes some extra fault codes to latch and you'll need a trained Volt tech, not a body shop guy, to reset them. I'm not sure why you would pull the disconnect at all. It divides the main battery in half but it does not discharge it. If the battery case is intact, it's not necessary and if the battery case is compromised, it's not enough.