yes to the PCL being accessible, yes to the brakes being accessible, and an almost certain yes to a brainfreeze in the cockpit.
Sometimes when people encounter something that they did not even consider as a remote possibility they freeze, and that is my guess (monday morning quarterbacking) as to what happened here.
It’s possible they were on the brakes, and due to the icy/contaminated condition of the ramp they were not effective. The PC12 has VERY good brakes, and it doesn’t take much to lock them up even on a dry ramp/runway. They very well may have had the tires locked up all the way to impact.