Wrong, should he have waited until a gun was pointed between his eyes. The aggressor wasn’t fleeing, he deliberately jumped the counter during a felony to confront the shopkeeper. It is perfectly reasonable to believe your life is in imminent danger at that point. The shopkeeper took action to stop the threat. When the robber accomplice said “I’m done, you got me, I’m dead, I’m dead.” The shopkeeper immediately stopped stabbing him and only restrained him at that point. He used the amount of force that was reasonable and necessary to stop the threat. Had both robbers ran and the shopkeeper chased after and stabbed them in the back it would be different. He followed the law. Criminals chose to rob and threaten him. You are for enabling them by tying the shopkeepers hands. You are the problem, not the solution.