Corrective action is not about 100% prevention, it's about mitigation or minimization of effects. For instance, I'll accept flight disruptions, irregularities, but not catastrophic loss of all aboard
I have trouble following arguments that don't include weighing of managed risks.
For starters I would like at least to revisit today's assessment of terrorist risk that was thought to be minimized by a locked door vs requiring a second person (FA) during breaks vs a single man cockpit, etc. etc.
I don't have an answer (opinion) at this point but I sure don't accept most other answers I've read at face value on these pages without more data.