Looks to me like a gimmick to dumb down (retard) learning.
It is harder to re-learn something that is first learned wrong than to learn it right the first time.
So, if doing a double-stop of red and blue strings it is a purple note? Learning how to communicate with others, and understanding the relationships of notes is integral in playing in my opinion.
Though I’ll admit to playing a blue note from time to time, and one of my all time heroes; Roy husky Jr. thought of musical moods as colors, I think I’m totally against this type of short-cut, short sighted, gimmick teaching.