Weight class across eras are tough. He has guys on this list who wrestled when there were 7, 8, and 10 weight class and he does not adjust for when weights were increased across the board. Guerrero was 126 which became 133.
Some of the guys on this list wrestled at the lowest weight class of their era and some at the second lowest. There appears to just be rounding going on here.
But what I find truly odd is that guys who won 100% of the time are tied for 8th (Ed Peery, Joe McDaniel, Mike Caruso, Ross Flood).