Unfortunately, I can't really figure out how this would work. The category in this case is not about a search term. The items I'm looking to restrict don't really follow a taxonomy in the normal sense; it's not about WHAT products they are, it's about WHERE they are, physically. There are, for example, DINING TABLES available for sale globally, that is, online AND in the physical store. But there are also DINING TABLES that can be bought only in person, in the physical store, and these are kept in a separate category called STORE ONLY.
Restricting search for the category STORE ONLY doesn't help because no one is searching for that. Excluding DINING TABLES eliminates my chance of selling a dining table to an online customer, and I sure don't want to do that. So the problem I have is, I'm not trying to limit what the customer searches for. I'm trying to limit what the search engine SEES. I don't want the search to see the STORE ONLY category at all.
Maybe it's easier to feed the pages to be searched instead? There must be a way for me to pull them from my site map and give them to your search engine. This process is complicated by the fact that the pages are coming in through a plugin but that shouldn't be a complete stop.
I have found one company that can do what I need, but it is an offsite search. The customer is actually take off to a page that looks like the site but is NOT my site for the search, and I'm not crazy about this. If the same thing can be accomplished here, it would be much better.