Sorry, I'm with Kerry on that one.
I have heard that the "fleeing" man was still carrying the rocket launcher.
The combatant, whatever age he was (and in the Third World they carry guns mighty young) was running off with a loaded rocket launcher. All he would have needed was a piece of cover to turn around and let fly. A fleeing person would have dropped the launcher when he had been shot.
Under those circumstances, I would have shot him in the back myself.