Did I say any different?
Knives are no longer a credible weapon.
Seems to me that, as many on here have said already, the single root cause of 9/11 was attempted co-operation by flight crews with hijackers, per the standard protocol at that time.
Solve the root cause, as we have by changing the protocol to active non-cooperation, as you partially allude to above, and any other fixes are pointless window dressing, or worse, expensive detractors from really saving lives at risk in the air.