I know someone that used to do that in Nam, working in isolated places and with at least one guard present. He joked that in case of trouble the guard was ordered to shoot him first, destroy the equipment, then try to quell the attack.
If Hemler had that level of clearance there's no telling how much info he's divulged over the years.
It's the people and system capabilities that could be compromised. Imagine your kid coming home from school and telling you a black Volga was following them to the house.