it should be easy to set up the system to make a loud noise if neither the flight controls nor the deadman are moved within a specified time.
It's already been done.
Such a function has already been around for years on some types ..it's called "pilot alert", "pilot response" or similar. Lack of pilot activity (usually the system monitors switch selections) after a predefined period(s) starts triggering warning messages and fairly soon thereafter loud noises.
However your still treating the symptom, not the underlying cause.