I note this paragraph from the article
Engine-failure 777 busts ETOPS limit
The FAA at present is working in co-operation with US industry body the Aviation Rulemaking Advisory Committee to draw up a new set of standards for long-range aircraft regardless of the number of engines they have, possibly taking modern twins into the 240min ETOPS range and beyond.
It looks as if since then the rules are simply re-written to allow twin engine aircraft to be used on routes where it is obvious that a four engine aircraft of a similar production date and safety features would be safer.