Fully aware that I am going to be stoned by everyone on here, but what is so difficult about this? It is retention pay, this has been argued ad nauseum on other threads and is the reason aircrew get flying pay, to keep them in the Service. If one chooses to leave why should they get paid retention pay? Perhaps they should continue to pay FRIs with no payback of service as well.... I can see that it looks unjust, but it is common sense.
As I said before, it would be better if aircrew were just paid at a different rate.