I think I'd put black epoxy in the hole, and it would look like an inclusion. The worm staining near the hole does not hurt the overall look to my eye. It just gives the gun character. You did just fine on this one. I think it will look neat when finished, but I would fill it so it will be flush to the touch when done.
That said, I am not normally a fan of worm holes. If a worm ate into a rifle, it would just look like a tiny hole, not a long
"track" down the outside. I am unsure how many builders back in the day would have used a wormy piece of wood, leaving those tracks showing. I am thinking few. Again, worm holes after the rifle is done would not be tracks, just a tiny hole.
My other issues are, "Is the worm or egg still in there?", combined with "How much tunneling is unseen, and is the wood stable/strong, especially through the wrist?"
That said, I think Top Jaw's gun shown here is gorgeous, and I would be mighty happy with that one. I am sure the owner is too.
God bless, Marc