sounds like a threat that was forseeable
Having to lift a 15 kg nav bag onto a shelf is a threat?
That's far from a difficult task for any reasonably fit person, and I dare say if you can pass your Class 1 medical it shouldn't be classed as a threat or problem.
Employers should have to provide a safe workplace, but I think this is the kind of thing that takes OH&S too far. Lifting an item the weight of a nav bag onto a shelf should not be classed as something that requires special procedures or assistance.
Edit: Sorry, I see from posts above he didn't have to lift it onto a shelf, but slide it out from next to his seat. That would require some twisting, I guess, but it's still not something I'd suggest is the company's problem. Any reasonably fit person should be able to do that.