Pugilist,
Fair comment, but these guys were showing some very demonstrable signs of mental deterioration, and falling asleep, sometimes constantly.
On one occasion I chose to go sick rather than turn up for work, I find that my own rest is disrupted because I don't trust the guy up front.
Routine tasks are performed fairly well by 70 year olds but anything out of the ordinary and the response is sometimes a blank look, or inability to carry out a task that entails memory or is mentally taxing