I was disappointed to read that they gave up the principled modeling approach (the 80-year old German paper mentioned early on in the article) and instead collected 100 data points that "looked good" and interpolated somehow.
The article says that the Kubelka-Munk model achieved color mixing that was "too realistic" and therefore difficult to use for the purpose of creating a distinctive brand palette. What this tells me is that they weren't looking for a model of how colors mix together, but a model of what colors look good together.
> "We know red and yellow should yield orange, or that red and blue should make purple--but there isn't any way to arrive at these colors no matter what color-space you use."
Well, that's clearly not true. In the HSL color wheel [1], orange is halfway between red and yellow, and purple is halfway between red and blue. Should have picked a better example.