My understanding of the purported reasoning behind the reversal was:

- They required airlines to implement cameras to monitor the hall leading up to the cockpit so that the pilot in the cockpit can verify who is requesting entry (without this, they still must follow the rule — Ryanair chose not to retrofit, so they continue to use attendants who can look out the peephole).

- In testing, they decided that the extra time that the cockpit door was unsecured during the switchovers in tight spaces was more dangerous than trying to solve the suicidal pilot issue with better mental health monitoring.

(My own note, we know that suicidal actors have no problems taking weapons to their copilots or whatever attendant is stuck looking out the peephole, e.g. FedEx 705.)