Having read information from this author before, it is just speculation about there being a pied gene. She is trying to equate pea fowl color genetics with guinea fowl color genetics which is again just speculation. I have not found any conclusive evidence of a separate pied gene in guineas.https://guineas.com/articles/genetics
" the less pearling apparent on a bird, the darker its background colour will be. So, the Royal Purple is the semi-pearled version of the pearl grey, and appears a little darker than it; and the violet is the non-pearled version of the pearl grey, and is darker again."
"it used to be thought that with peafowl, one white gene (T) led to a pied bird, whilst two (TT) gave a white bird. However, it is now apparent that you need both a pied and a white gene (PT) to get a pied peafowl, or two whites (TT) for a white bird. Peafowl with two pied genes (PP) are known as "dark pieds" and signal this effect by appearing to be a "normal" non-pied bird but with a few white flight feathers; birds with just one white gene (T) again look like a normal bird with white flight feathers (usually fewer in number than in the dark pied)."
clear as mud?
The trouble with guinea fowl color genetics is that far too much of it is speculation and too little of it has actually been proven through research.