It's amazing the mental gymnastics that people will go though to find a possible situation where the act wasn't intentional, and try to refute new pieces of evidence.
And then go through more mental gymnastics to come up with schemes to change the cockpit door lock. Either you the cockpit is secure from the
meat passenger compartment, or it's not. You can't trust the general public to make the right decision as a whole in an emergency. A few will rise to the occasion, the rest are idiots. If there is some sort of override code or codes, that's relying on the flight crew to potentially resist torture, or other deception. Or some sort of majority system involving passengers? 6 people with guns, stand up on a plane, grab 6 children, say they are only interested in taking over a plans for negotiating the release of some prisoner, and aren't trying to crash the plane, can you count on a majority of the people to make logical, non emotionally compromised decisions?
2 man rule to prevent rogue incidents like this, lock it down so there is zero chance for unintended access to the cockpit. That way there are only 3 parties that need to be trusted. Also, how about not over working and under paying pilots so much, I mean really, how many people per week do they move, even $0.50 per ticket extra divided between pilot and copilot would be significant.
Is there still risk? Yes, but you did drive to the airport that morning, so you must not be *that*adverse to risk.