Related Content -- security to prevent accessing query results?

One of my users created a related content menu item that uses a query written in PS Query. However, another user is able to access the query results even though that user does not have access to Query Manager.

In the Related Content Service definition, security option “Related Content Consumer Security” is selected.  According to PeopleBooks, this uses the basic PeopleTools security model so the user should not be able to display results of the query.

Does anyone have any ideas on what the issue might be?