PFP - I agree, could have been much worse. I just didn't want to overstate what did happen.
My impression is that when they were waved off by ATC during descent because airport was below minimums, they had already turned on the high-altitude option, set to airport elevation 14000, and then forgot to turn it off while holding.
I've been up to 14000 feet here in the Rockies - and the brain definitely gets mushy and full of cotton balls above about 12000, even though I'm acclimatized to Denver's mile-high atmosphere.