Don't know exactly what in my post you were pointing at but you can't just vacate FL210 without clearance to do so. You aren't VFR at 210 regardless of how crystal clear it is out there.

I was saying that if they did have communication failure then they should have done AVEF (assigned, vectored, expected, filed) while squawking 7600 then flying the full procedure into the airport. These guys obviously had zero situational awareness or they should have known 70+miles back they should have started descending(hinting they were asleep). They didn't, they didnt realize they passed the airport which I'm sure would have been easily visible on the FMS not to mention they are passing an island in the Pacific. It's not like you're over west Texas where the next 100 miles look just like the 100 miles behind you so it's easy to get confused. Center would still have tried to contact them on their old freq. as well.