For Flight_Engineer - your assumptions and conclusions are incorrect. Whilst death is an outcome for everyone and its all cause rate after a certain age approaches 100% (somewhere near 117). This does not then mean that the risk acceptance threshold changes or if your other condition risks are less than this then the system is flawed. As before, the risk decision is composed of the full view of the "rate of unacceptability at which the hazard is realised when an appreciation of the condition in the environment is made with respect to the standards acceptable within the safety management system. This rate is whatever is set by the regulator and it is the best that can be made with the scientific, not single expert, knowledge available". Yes death is a single event, yes it is pretty bad (for the individual and whoever is nearby in the aircraft) but whilst the individual effect is large, the statistical event risk is lower than a plethora of other safety significant events (or risks of events).
The hazard is not death (although that is an outcome), it is the condition or treatment causing impairment &/or incapacity &/or death &/or the aviation environment effects and/or mitigations on the condition over the term of the licence.
I would be surprised to hear of anyone flying on a Class 1 CPL/ATPL internationally over 65 and domestically without investigations every 6 months and would also be surprised if companies employ them (in a passenger flying role) over 70 (and only domestic multi-crew) at all for broader insurability reasons (partly due to that all cause death rate you raise). Noted though there are some QFI/FIs flying students well into late 60's/early 70's, again with some pretty strict conditions.
The proposal of "never tell anyone" about medical issues and describes an attitude of wilful violation of the broader safety system and a lack of integrity. The, "I know best" and "if you mention anything you'll be grounded" combination will undermine safety even when there isn't mistrust in the system- and there are no quick fixes when those under regulation actively undermine that system. It is also under-appreciated that the decisions that are made are in the broader public interest rather than the individual.
It's nowhere near perfect and people will be upset, your response to actively mismanage one's own occupational healthcare puts others lives, property and reputation at risk in a repugnant and self-indulgent way that no one would reasonably support.
If you transcribed some of these conditions under discussion to the engineering space and started talking about 15%, 40% yearly failure rates or degradations of critical engine/flight surface parts then I'd say there would be some spirited discussion of continuing to use those parts...
Vis your magical Jim, no idea what the detail is. You could very easily sign off on anyone on a class 2 for VFR, daytime flying in remote contexts and then restrict the operating area - i.e. cattle surveying/remote property access work in a defined area and then add on multi crew restrictions or time limits, whatever mitigates the risk, in context, to an acceptable level. If the risk is indeterminate or there are multiple risks/risk factors then a conservative approach is always going to be the case. The other considerations though are much lowered if the only victim is yourself and your private property. Similar processes occur in the road transport context. The regulator is not going to do the legwork to demonstrate or research these mitigations without government direction.