Understandable. There's a lot of misinformation floating out there.
Since silkie feathering is a recessive, it would keep showing up in full as the birds are bred together.
Not to mention all the other silkie traits that would potentially pop up: crest, muff/beard, extra toes, fibro...
I haven't heard of anyone in the Genetic Hackle Fowl community having silkied fowl pop up.
What I had heard was specific to Whiting's lines, not a generalized GHF community breeding strategy, so not hearing about it popping up in other lines doesn't completely rule it out unless they acquired birds from him. Since it's a fly-tie business I highly doubt he shares any of his genes to prevent competition, so who knows what random things pop up in his flocks and are culled.
Not saying that this is a fact, it could very much be misinformation like you said. It's just something he'd only be able to verify, really, unless someone else has birds from his lines.
According to what I've read, there must be a different genetic basis for the barbicel differences in a GHF feather.
That's actually what I was wondering when I brought it up! If the silkie info was true was there another gene possibly associated with the hookless gene that affects the rachis? One that was possibly semi dominant or even dominant that left the recessive hookless gene easier to breed out? I'm almost certain it was the rachis of the feather that was specifically mentioned, I believe it prevented twisting or made it more malleable or something along those lines when being made into fly-ties.
Do silkies even show that trait to begin with?

Honestly I know nothing of fly-fishing so I have no clue what feather traits are ideal for fly-tying. I just know genetic hackle fowl are beautiful birds! Love the picture you included.