There is no way to check if the user is ADMIN or USER. I explain:
Since the checkbox "ADMIN override security" is off, the ADMIN has the same rights as a USER. The only difference is that the ADMIN can access and modify the Document Properties (and hence these options) as well as save the QVW file and the USER can't. In client-serve mode, there is no ADMIN mode at all, everyone is a USER, this is because you can't modify a QVW via a client-server connection.
A solution to you case might be to add an attribute field with role USER or ADMIN (like a restriction field) linked to each user defined in the section access.
