Dick Smith, rather than sourcing your arguement from Quora, why don't you try one of the other regulators,
EASA: AMC 20-6 rev. 2
Extended Range Operation with Two-Engine Aeroplanes ETOPS Certification and
Operation
I welcome a critique of the certification specifications.
Have a good read of that document, especially the rationale behind ETOPS maximum diversion time based on in-service Inflight Shutdown Rate (IFSD) - this is what determines the maximum ETOPS time interval, a probability based assessment.