I'm still not sure what exactly he means by "dynamic" in "dynamic proportion"; that the numbers (percentage) change seems too simplistic; I'm willing to bet it's more than that. (Warning: we are getting deep into my own interpretation.)
If you choose pleasing hues with value in mind, and pay attention to the amount of each and placement, one can create a kind of cloth where the eye travels over the surface of the cloth, on the strength of the colors alone, (rather than relying on the weave structure, which is how this is more commonly done.) Ergo, "dynamic".
Randy didn't use the word "dynamic' in the workshop. Instead he repeatedly told us to weave in a "painterly" way, to surprise him, and used many beautiful musical metaphors. I'm not sure if I'm placing too much emphasis on the one word that bugged me for months, but I can see when it's working.