Jake, I cannot answer for Dennis, but I used, besides glass and kevlar, at least 2 layers of carbon for my hull skin-laminate.
And on the places where bolts came through even double or triple. (My hulls are not hollow,but have a solid foamcore! So bolts are fixed and glued from inside)

So, your remark is spot on. I wondered already a few years ago where the rust came from. It looked like from inside, because painting it over with 2-C PU paint didn't help at all.