Bolt owners may not want to leave their EV's on to charge in the attached garage while vacationing.Agreed.
Your battery will try and keep itself at a somewhat "optimal" temp, this is why if you park an EV and leave it unplugged for too long, you are coming back to a brick (well, one of a few reasons, but a big one).
I think that is their fear and why they make it clear "unplugged" for the long term storage thing. I would generally advise anyone that won't be driving their EV for a week or more to make sure you have it plugged in, just in general.
sorry couldn't resist adding this in there.