I think he's saying that as absolute incomes get higher, commuting cost as a percentage of income drops, because commuting cost is largely fixed regardless of income. And so it makes more sense to live in a low-COL region and commute to a high-COL region.
For the average person, flying to work every day is unrealistic. If you are making $1M/year, it suddenly becomes very realistic. Same day roundtrips between SFO and Seattle via coach are about $200 when purchased 3 months out. Times 200 workdays/year, that's only $40K/year. You end up way ahead financially buying in Seattle and commuting by plane to your job in SF, if you're willing to stomach the ~6 hours/day of commuting time.
Then if you don't want to spend an hour and a half in the terminal, you can fly private jet. Private jet time apparently runs about $5k/hour. At ~600 hours/year, you're looking at about 3 million a year to commute by private jet from Seattle to SFO. Still out of your price range at a million in salary, but quite doable if you were making say $10m, and your commute time isn't much worse than sitting in traffic on 101 between Google and the Marina.
Replace Seattle with Las Vegas and all 3 of (housing, flight time, expense) get better. Round-trip to Vegas is about an hour and a half; coach prices go as low as $59 and private jet prices would be about $1-1.5M/year; and houses can be had for $200K, freeing up lots of money for flying.