Andy:
I think Shiskine hovers right between a 4 and 5 on the Doak Scale. Perhaps Tom, like many of us, is softening in his dotage.
An initial 2 was too low, but as I've revisited his scale, and read his comments here and elsewhere about the nature and intent of the scale, I think he's right to hold even courses rated as 4s and 5s to fairly high standards. One of the things I think is sometimes lost in debates about the Doak Scale, and assessing courses by it, is that it's a purely golf -- and, really, golf architecture -- ranking. And those who might rank Shiskine on their own personal scale -- it was one of the more enjoyable courses I played in Scotland -- often think beyond strictly golf to things like value, scenery, setting, and uniqueness that push it higher on their list of course to play. (I'm a sucker for quirk -- but most golfers aren't.) Tom's initial thoughts on the thread you linked to are probably correct -- you'd have to play a lot of courses in Scotland before Shiskine is the best one left to play.
Still, it's a great setting, and a true links, and scattered amongst its 12 holes is some really terrific golf.