I do not remember that MacKenzie wrote much of anything about "finishing holes" as a separate species. If you wanted to posit, based on the finishing hole at Cypress Point and Pasatiempo, that he didn't share the modern preference for a long and difficult par-4 at the end, that's probably a fair assumption, but I think it's safer to say that he just didn't worry as much as some others about what the finishing hole was. Crystal Downs also finishes on a shortish, dogleg par-4 -- there is a theory that Maxwell actually changed the design of that one -- but, in contrast, both of the 18th holes at Royal Melbourne are difficult par-4's, and the 9th at Augusta is no slouch.
Remember, too, that MacKenzie wrote mostly about design for the enjoyment of golfers, not about golf as a championship test or as a test of character. His philosophy was certainly different than the founders of Oakmont.