your logic 😉
I am sure, it it possible, haking the search logic or building your own role, but one question : Why would you want somebody to find a document but not allow to view it ? Because viewing and downloading is the same thing - except if you use a special viewer as proxy.
The meat is, though, in all other settings, I would consider it a massive breach of security, indexing and making available a document I have no rights to see. Because via the search queries, I can still find out, if - for instance - my name is in the list "peopleToWatch.xls".
Regards, Norgan