I can't think of many social norms or government rules worse than ones that consider it despicable or, as you say, "unspeakably wrong" to have a right to defend yourself. The example of the grandmother in your text should be a clear case of someone doing exactly what is the only obvious thing when the policing system has failed at its job but criminals continue to victimize. What kind of absurd, twisted logic would claim otherwise to a constant victim without protection by the state?