Several evidentiary issues here. In general, the burden of proof is on the party asserting existence. Is there any evidence that the FAA’s aeromedical regulations improve the safety of flight? None has been presented so far. As noted, it is very difficult to prove a negative (that is - has no such effect), which is why such a general burden of proof exists.
OTOH, there is a presumption for the status quo, especially when proposing making changes. I think in this case that would suggest careful studies (which so as we can tell, have never been performed) and proceeding carefully.
The fact that we have in the US the safest commercial air travel certainly suggests something works well in terms of safety. But that in and of itself does not mean the FAA or government regulations are responsible. There are myriad possible causative factors. Indeed, it appears that a primary factor has been improved procedures and training. A government bureaucracy attempting to ensure medical safety may have little or nothing to do it.
A good reason to consider this more carefully is that there is a large body of work on the inability of coercive regulations to achieve their intended effects generally. This is often due to unintended consequence of the coercive regulations.
In terms of aeromedical regulations, this would be the many pilots who may avoid receiving medical care because they don’t want to jeopardize their medical certification. Since the number of such pilots may vastly exceed the number of pilots such as the GermanWings pilot, the negative consequences of the former’s behavior may exceed those of the latter group. In that case, the regulations, while well intended, would actually _decrease_ safety overall.
These can be treated as empirical questions, but have not been due to strong emotional reactions to high profile disasters.
In general I would certainly agree that passengers on commercial airliners deserve not to have pilots having psychotic reactions in the cockpit. I just am not convinced a coercive regulatory regime is the best way to achieve that. It may be better to have a greater role for market forces.
As to “my opinion is iron-clad”, please correct me if I am mistaken, but that would seem to suggest your views are fixed and not amenable to facts or reason. Is that correct? If so, I don’t imagine this or further discussion will be of interest. Apologies then, but hopefully my thoughts may have been of interest to other readers.