I find it interesting that (as of this point) comments that speculate on health are downvoted, but comments that speculate on his relationship with management are not...
People tend to empathise with that which is more relevant to their own lives; more people will have a bad relationship with management than bad health.
Why not both? Bad management can lead to bad health. But I don't think it was only management - it was the rank and file that didn't want to change as well. Trying to fight an entrenched system could definitely lead to illness.