What we haven't talked about here is the use of the rather arbitrary definition of what a "classic" course is. Golfweek is using anything pre-1960. Is this the accepted definition? I'm sure this is a rather subjective area for most of us. If we are using dates I would think earlier, perhaps pre WWII.
I remember Brad Klein telling me at the time that 1960 was the midpoint of age for the 14,000 courses in the U.S. when he started doing the lists. That, plus Pete Dye's career started about 1960, so they don't split his designs between the two lists. [The only designers who could plausibly have courses in both lists* are Dick Wilson and RTJ, and neither of them does.]
I suppose you could count everything from the 1960's and maybe the 1970's as "classic" and start the "modern" section with the TPC at Sawgrass c. 1980, but that wouldn't affect the lists all that much, would it? It would move The Golf Club, Crooked Stick, Harbour Town and Muirfield Village [and maybe one or two others?] over to the Classic side, and make room for a couple more in the Modern.
* I realize there are a few courses in the Classic list that are really modern redesigns, and a couple are listed with their modern designer, but that isn't plausible.