Did you do a full workup with chart history, labs and physical? If not, how did you determine he is healthy?
Most medical conditions, even serious ones, do not present so conspicuously that a casual observer would know what was wrong. Being able to walk and talk does not necessarily give one a clean bill of health.
Guess I just assumed he was scamming the system since I know four people in my small circle who received ssa disability even though they were as healthy as me.