Watch one of his recent construction videos where he amps up over Code 100 vs. Code 83 in HO.
I watched that... I thought it was funny, but I can see how that might turn off some folks. He's correct that well-painted, ballasted, and weathered code 100 can look quite good. That said, being out of the HO standard gauge gig for a long time now, I don't know if the rail profile has changed. To me, the issue with traditional code 100 track was the rail profile...similar to N scale code 80. I feel that the rail profile (lack of a web) will do more damage to realism than the rail height. If the concrete code 100 he's using has rail-shaped rail, then I say "vaya con Dios."