I think not. Yank the T/C fuse from the RCM, this simulates a failed relay or fractured solder connection in the feed to the brake controller - you will get EXACTLY what he's getting.
If it was the speed sensors, then he could take it out of park - but since he cant', it sounds like both the interlock and brake controller don't have power - and they are both fed from the traction control relay on the RCM.

My Logical conclusion: He has lost power to the brake controller and interlock due to a failure on the RCM

Try yanking that fuse on the RCM. You will need the tool to get out of park. Take the car for a ride around the block - you car will do just what his is doing. I know.
I tried it one night.