AnFI, if you intend to quote someone, perhaps you should provide a reference or justify your statement:
If their engine were to stop, for some strange reason, then their chance of survival (according to JimL) should be 10^-9.
You need to explain why redundancy with pilots, does not add unacceptable complexity!
Redundancy is only required when a component (or system) doesn't meet a specified reliability target
and the consequences of failure is not acceptable - to some criterion.
Protection of third parties is the highest priority with aviation Authorities; the next is CAT passengers.
To my knowledge, there is no regulation that prevents a pilot, of other than a CAT flight, from flying over a sea area where a failure of the engine or another system would result in a hazardous or catastrophic outcome. Rules of Air kick in
only when third parties are exposed.
Jim