I tried that before. The offer was lower than I had hoped, unsurprisingly, but to their credit they were honest and suggested I'd be better off selling privately.
Much better than the time Anderton's offered me £75 for my Epiphone Elitist EB3...
I've always taken that with a pinch of salt. If you pick the string then hit it with your thumb you get a pinch harmonic - something CS certainly used as an effect from time to time, but it certainly wasn't a main part of his usual tone.
If you look at the Master Licks (?) Video on YouTube CS describes and demonstrates thd technique.
It's so good to hear these concerts presented properly after years of (admittedly pretty good) bootlegs.
So impressed I was with Pegg's tone I actually started a thread about it a few years ago...