Arm
You are right, the only thing he has to argue is that it allegedly happened in the work place.
In my case I found that I had a dodgy lower back as a result of many years of swim trianing and surfing. This apparantly has your lower back in an unsupported manner and over the years unless you compliment swimming and surfing with other preventitve exercise it will eventually get you. I just swung my legs to get out of the car and bang i was stuffed, couldn't move, had to get someone to pick me up.
If the guy legitimately hurt himself at work doe to his flight bags then fair enough. I just think it might be hard to prove. Then again lawyers will suck up tens of thousands arguing the point.
It is a reminder to all that along with loss of licence you should buy income protection.