And what does this have to do with colors being spectral? If you look at the cie chromaticity diagram you can see that yellow and cyan have wavelength corresponding to them while purple does not.
You probably think I'm being pedantic. But the point of the article is to conceptually distinguish color from wavelength. If we're going to distiniguish them, we might as go all the way. There's no reason to bind yellow (and cyan) to a single wavelength, while magenta gets special status. All three are secondary colors and all three are composites.
This is important because privileging magenta does not generalize to higher-dimensional color-spaces, and therefore impedes to our understanding of phenomenology.
The RGB model that is currently used (sRGB) is just an emulation of CRT-displays, it is not how human vision works. There is not actually much conceptual difference between red and yellow.
The model is irrelevant to my point. E.g. Lab and Cieluv may become obsolete if it turns out that we can remap "the bindings between color and wavelength" in our brains as easily as "the bindings between color and wavelength" in our vision libraries. The fact that purple doesn't associate to a wavelength should be a clue that binding the two at all is a mistake, not a clue that purple is exceptional.
This is important because privileging magenta does not generalize to higher-dimensional color-spaces, and therefore impedes to our understanding of phenomenology.