Wow, there is so much to digest in that article, utterly fascinating.
I had no idea Alister's brother was involved with Chandler Egan up in Portland at the Lake Oswego gold course, which is a highly regarded course on hilly ground, mostly clay. I have not played it yet, but will have to get something arranged.
I assume this took place in 1925, when Vernon Macan was working on Columbia Golf Club (today's Columbia-Edgewater Country Club) at the northern end of town. Somewhere in there Egan also built, if I recall correctly, Eugene Country Club south of Portland, and Indian Canyon over in Spokane, Washington. Now I wonder if Charles Mackenzie was involved in those courses!
It's also interesting about the 8th green at Pebble Beach - I'd always heard that Alister did that design work, now it sounds like Charles did it with C. Egan.
And last...the rationale for the flat greens of C. Mackenzie on a couple of courses is the flat nature of the overall terrain. It's possible Charles was a better builder than architect.