The report was posted at bobistheoilguy.com. The poster said that the oil was only in service 20,xxx miles and that the mileage was a typo.
Bypass filters take a slipstream of oil from the system and run it through a very fine filter (50+% efficiency for one pass at 1 - 5 microns for instance). The entire stream cannot go through the filter at once, as the pressure drop would be so great you'd ruin your engine. Full flow filters generally filter to about 25 microns, give or take, and allow the full flow of the oil to pass through with an acceptable pressure drop.
I don't know why someone would be so foolish as to go twice the manufacturer's recommended interval without analysis. Perhaps he thought Amsoil or the bypass were magic? Perhaps he was taking his advice from someone who thought he had something to prove? Perhaps he thought $20 for an analysis was too much to spend when speculation is free?
I am glad common sense got a hold of him at 20,000 and not 30,000...or never!
Tim