I suspect Ulster that the OP will respond that if people live another 30 years after being grounded then they aren't about to have a stroke nor a heart attack etc etc
Perhaps the point that may help is that apart from needing to prevent pilots flying because they are at risk of sudden incapacitation, we may also need to ground them for medical issues that will not curtail their life but will make them dangerous in the air. Examples that come to mind are
Field defects - if you can't see the left half of your visual field you may well put the wing of your aircraft into something
Drugs - if you need drugs that have a risk of sudden psychosis or other side effects
Stable diseases that limit your effectiveness such as Parkinson's - yes you can live for 30 years with it
Personally I don't give two hoots what the passengers think. They are as likely to be rational about health as they are about anything else. But the idea that doctors don't know what they are talking about, although sometimes correct, is just plain daft in this context