What I agreed with overall was his take on what gear inches for a given type of touring situation, and that for an "expedition" type tour (tougher roads, steeper gradients, probably more weight on bike) he suggests 18g.i as this reflects my experience.
I too agree with the 9 speed view, and I would go that route also, 10 for trips around here. Like you I would go mtn bike crank also, 44/34/22 would be my preference, and cassette wise, would depend on the trip.
It's just too bad there aren't common 9 speed 12-30 or 32 cassettes that don't cost an arm and a leg. I'd go 26in for off and beyond, and would want about 18gi so a 30 would be a minimum.