I understand why there has to be discussion on this but I lean toward Bob's position. The man was remorseless and promised more death and destruction, so any police trying to storm his location would be subject to injury or death.
What I do wonder (and forgive me if this is mentioned in the article, which I haven't had a chance to read) is why the robot couldn't have fired a strong tranquilizer and put the perp down that way. On the other hand, if he was wearing bullet armor, the target areas would likely be just too small.
Dunno. Easy to second guess. My husband, though, echoes my own thought at times: When are we going to capture some of these lone wolves and try to learn more about what makes them tick, perhaps help prevent another incident somewhere with the knowledge gained? Not likely, I realize, but still.....