It is heartening. Perhaps not surprising, though. I find it hard to think that anyone would advocate sacrificing your own life just to keep from hurting or killing an armed attacker.
What frightens me are those who want you to submit to an armed attacker, in order to "keep him from killing you." In my mind, if you are confronted by an armed attacker it's a coin toss as to whether he will kill you, regardless of any actions you do or don't take. Certainly, the opportunity to do something may not occur, but if it does you should be prepared to take it. And when you take it, be prepared to kill. An armed attacker must never be considered out of action unless he's either unconscious or dead.