I'll bid on the anvil.
In looking at the pictures of all of his brushes I wonder if he is trying to have a band of epoxy between the handle and the exposed knot. All of his re-knotted handles seem to have the same degree of "enthusiastic" epoxy use.
I guess if epoxy doesn't squeeze out of the top, you can't be sure that the plug is set in epoxy. Or something like that (?). One thing is for sure; he is staying busy building those brushes.
And evidently keeping the epoxy manufacturers well into the black.