Do you notice a common thread?.... Direct contact.
Look, I posted facts about zinc. Whether one wants to use it or not, is a personal choice. Plain and simple, there are no issues with using galvanized fittings in a smoker. Not grate surfaces that are in direct contact, but screws and nuts are not an issue.
Yes, I noticed the common thread. I wouldn't hesitate to use galvanized fasteners, except maybe directly over the meat where dripping could be a problem. I would even patch holes in the sides with galvanized and I already use it for smoke ducting. The NSF has a pretty low opinion of wood, but lots of people have smokehouses made of wood.