The "any bad gunman could precisely as easily have used a knife" claim never persuades me. Guns make killing so much easier. That's sort of the reason why the gun was invented. It's an cute claim, the "bad gunman minus gun equals knifer" assertion, but has anyone ever actually proven it as consistent behavior in killers? Just wondering.
The Poplawski incident happened in my home town. As I left Palm Sunday Mass, I noticed a police officer coming in for the next Mass. If you want to assure that officer that Poplawski could just as easily have killed three and injured two with a knife, go ahead.