With a program like that in place, the only thing that keeps them bound is they’ll wanna go home to fight again. If there was some sort of mechanism that could be generated that guaranteed they couldn’t fight again, POWs would become more of a processing thing than years of being abused.
I recall reading that during our Revolution and our Civil War there was something called Parole. This was granted to captured British soldiers. It may have been reserved for officers as Parole was granted to men of honor whose word was respected. They swore not to return to the fight.