I'm not going to accuse him of misrepresenting anything, but I fail to see how the practice of "precision scheduled railroading" (PSR) has anything to do with the length of the trains these railroads are running. If anything, the whole system has gotten more efficient and the railroad supply chain has become more streamlined by eliminating classification moves in intermediate rail yards between ends of a haul.
Train lengths are often limited due to the length of passing sidings.