Extended Access - View Only for some System Functions

I have found that it is currently impossible to grant 'View Only' extended access to some of the system functions within People HR. I was hoping to grant view only access to employee documents for a particular manager, but the only options are 'None' or 'Update'. I can't see any reason why 'View Only' wouldn't be an option already? It is very frustrating as we do not want these record tampered with by a manager.