He missed moment of inertia. Bike with nut spun up against the cap will accelerate faster than nut tight to rim (by an exceedingly small amount).
I also think he missed a benefit of one nut in and one out. I think that makes it slightly harder to shear off the valvestem as the wheel is only touching the metal stem. With nuts only on the cap side of the stem, with many rims/tube, I think you can get in a situation where you have the metal rim touching the rubber tube (which doesn't last long).
I heard that comment and was confused. I suspect that was just a specific painful combination of rim/tube/tire. We all know some are easier and some are harder to get together. Lifting the tube by 1/8"(or maybe 1/4" as that taper didn't seat?) in one tiny spot should not make it impossible to assemble. Maybe the stem was the final area to seat and the beads were trapped between the nut and rim? Pull up on the tire so the stem side seats first and the nuts shouldn't affect mounting at all.I've never tried a nut on the inside and outside of the rim, but he claims he was unable to seat the tire bead that way.