Pritzker jury will not revisit decision to exclude Denise Scott Brown
... you're conflating history a little bit. All the names you list (excluding Siegel) are involved within "FIVE ON FIVE" a feature within the May 1973 issue of The Architectural Forum magazine, from which the notion of "whites" vs. "grays" followed.
Here's the short introduction to FIVE ON FIVE:
Constructive criticism has long been a characteristic of the Forum. So has constructive candor. On the following pages, the work of Architects Peter Eisenman, Michael Graves, Charles Gwathmey, John Hejduk and Richard Meier--published in Five Architects (Wittenborn, 1973)--is criticized by five other architects. Robert Stern organized the team of critics because he felt that Five Architects presented an opportunity (too rare these days) to discuss current architectural attitudes. It is only to be expected that Stern sought a team whose orientation is more or less opposite that of the original Five--a stance that could be loosely described as sympathetic to the Yale-Philadelphia Axis, meaning Louis Kahn and Robert Venturi. It is the Forum's position that confrontations between various philosophical camps are much needed, and sallies like the ones you are about to read not enough with us. Thanks are due to the original Five, of course, for being so sporting.
The labels of 'white' and 'gray' were 'established' later to differentiate the two 'camps' and Venturi and Scott Brown were (for sure) in the gray camp. Louis Kahn died March 1974.