Interesting to compare with ETOPS (good maps: gc.kls2.com) which governs how far away from acceptable alternate airports a commercial plane can be. It corresponds to safe flying time with a single functional engine. So a lot of the area in some of the larger Voronoi regions, especially in the Southern Hemisphere, is actually unreachable by any commercial flight from the closest airport.
It's worth noting that ETOPS only applies to 2-engine aircraft; a 4-engine aircraft can travel outside the ETOPS-permitted areas as long as it has enough fuel.
When people say "ETPOS" these days, it's understood that they're talking about the maximum distance an aircraft of any size can fly from an airport - various regulators still apply such restrictions on aircraft with more than two aircrafts.
I thought it stood for "Engines turn or passengers swim"
I'm not sure I'd like to be on a plane 6 hours from an airport -- better hope you don't have any sudden medical requirements that would lead to a diversion!
