I completely agree with you that there should be no legal requirement to warn an intruder before utilizing self defense. I just feel that its nuanced, and in this particular case, if I was the homeowner I would be screaming my head off warning the intruder that they are about to die in not such a polite way. I just would feel morally obligated to do everything I could to divert the situation, and I would hope most others would do the same before making the decision to end a life.