Arguments regarding seletion of an alternate during EDTO/ETOPS can be settled by reading FAA AC 120-42B. It may use the old terminology but it is still in effect. It explains in plain English with examples what are, and are not, acceptable reasons to select a more distant airport for diversion. EASA does not have an equivelant document but a broad reading of all their regs delivers the same message.
Hint: You need to be monitoring all suitable airports on your route, not just the ones the dispatcher plucked to make up a flight plan showing the aircraft could legally dispatch.