Regulatory, indeed
I only wish to concur strongly and emphatically with the points Nigel on Draft has made in the two (2) most current posts. The question of fitness to fly a certificated air transport category aircraft is a matter which must be regulated by each State's national laws, policies and regulations. These in turn must be (if the State is a party to the Chicago Convention) consistent with and faithful to the ICAO Annexes, SARPs and related guidance. However.....as their name implies, SARPs include not only Standards, but also Recommended Practices.
Solving the problem of cockpit access will not be easy. Every State with a major civil aviation sector naturally will tend to -- confirmation bias? -- favor its own way of thinking about such matters. But, uniformity is an underlying principle of the current international civil aviation order. And ordinary, or routine if you prefer, processes in this arena - whether at the EASA or FAA level, or with ICAO at a more inclusive international level - do not move quickly.
But solving the procedural and mechanistic issues around FD access will seem simple, compared to reform, if not "systemic reset", around mental wellness, fitness to fly, and questions of mental illness.
One thing everyone does agree on, or should agree on IMO, is that knee-jerks produce pains where discomfort was not within the scope of the knee's, or the jerk's, intent.