Yes, you are correct Jeff. That's exactly the big misunderstandment.

Carbon laminate is a mixture of carbon fiber and resin. At the surface of carbon made part their will always be the last microns resin at the surface. Which electrically isolates. So you can let a aluminium traveller rest on a carbon laminate surface for a century and nothing will happen.
(Yes,I know saltwater surrounding will demand more isolation in order to prevent leaking-current, which may blow through)

But if you are drilling holes in the carbon laminate, then you indeed create vulnerable spots for galvanic corrosion. So, a responsable cat-manufacturer takes care for that before rivetting the traveller on the beam.

And after drilling a rivet out, you have to isolate the hole again with resin, or other isolator.

(Don't want to be the wise guy, but epoxy filler on the washer will do that trick too)