What I quoted from PB&G just means is that the female salmon pigment in e+ & wheaten hens is a different phaeomelanin pigment as found in males (& probably different to female neck phaeomelanin pigment too). So with this information, there is no reason to jump to the assumption that red wing bow pigment in that particular rooster is the same as female salmon pigment?
Some Silver Wheaten lines have an extra phaeomelanin intensifier (eg as in Salmon Faverolles, etc). This is not eWh/eWh S/S or S/-, rest wild-type as other Silver Wheaten lines have clean silver roosters & medium salmon shades in hens.
There are multiple threads here at The Coop that mention that various red intensifying mutations seem to be able to cause red leakage on S - silver based birds. S is a leaky gene. This red leakage can occur on eb based birds too (where hens don't naturally have salmon pigment). So the salmon pigment compound as found in e+ & wheaten hens is a different issue.
It's more to do with the sexually dichromatic phenotypes in chickens: the placement, intensity & type of phaeomelanin with each gender, and what effect each mutation(s) (& combinations) have on these wild-type male/female phenotypes. There are many, many genes that go into the make up of these wild-type male/female plumage colour/pattern phenotypes.
P.s. - there is often no direct correlation with sex chromosome Z genes to the main differences in sexually dichromatic male/female plumage colour phenotypes, and autosomal genes also influence this as Wieslaw has indicated with Hf (an autosomal mutation that switches on aromatase in males). The homologs of chicken sex-linked s+ gene (SLC45A2 or MATP) are found on autosomal chromosomes in mice and humans (ie chicken S locus equivalent in humans & mice are autosomal in the latter two, not sex-linked). So it is quite complicated.