Ben Crenshaw was on the GOLF Magazine panel for a lot of years, but took himself off about ten years ago, just before Sand Hills was up for consideration.
Bill Coore declined to participate a couple of times, for the same reason. I think they believe their names on the panel would somehow cheapen the ranking of their courses, despite the fact that no architect can vote on their own.
There are 14 architects on the panel, according to the magazine. (Apparently, by my tally, they counted Nicklaus and Weiskopf as architects, but not Palmer and Player. :) ) The only one I know who has played Pacific Dunes is Dana Fry, although there may be one or two others -- not a large sampling.
Certainly there is a bit of professional jealousy involved. Practically none of the modern courses were voted as high by our fellow architects as by the panel as a whole, and that's understandable ... we all favor our own style and viewpoint. And there's always someone who might throw in a negative vote just to keep the playing field more level ...
I'm sure not losing any sleep over it. The ranking on the big list is the one I'll show my next potential client.