I'm happy to be wrong. I just referenced CAO 82.0. Perhaps CAO 26 trumps COA 82. I'm not sure.
Please show me the references.
When an ETOPS airport becomes unavailable during cruise, we always had 3 options: turn around, divert to remain in ETOPS coverage of an other available airport or land. Of course with 2 engines operating, and engine failure probabilities being low, we would most probably keep going if time intervals were reasonably insignificant.
Either way, here we are talking about a specific airport pair, both available, and what is or is not considered to be an acceptable risk.
Like I said, I deal with this a couple of times a month and my licence is on the line every time.
Perhaps I'm about to be re educated.