No.
It is is not a fact (i.e. "correct") but rather Geoff's relatively informed, very plausible, but probably slightly biased (i.e he wrote a book that he was trying to sell) opinion of 10+ years ago.
If there were a "Mt. Rushmore" for GCA's, Dr. MacK would be on the short list, but so would OTM, Park Jr., Ross, CBM, Tilly, Maxwell, RTJ, Dye, Coore, Doak, and probably a few that I have forgot. To fit in all those worthies on one mountain top, you'd probably have to expropriate the unfinished Crazy Horse monument a few miles south of Mt. R. But, would that be the right sort of tribute? Rather, maybe near some shrine of golf you could build an 18 hole course that gave homage to each of the above and the others that I have forgot (e.g. Flynn, A Simpson, T Simpson, Wilson, Sutherland, Braid, ANOther...).
I would propose St. Andrews, Castle Course. Blow that monstosity up and build a tribute course as per above over its smoldering ruins...
Rich