Quality Clouds only needs access to the sys_user table to report aggregated statistics about the number of active users in the instance, and the distribution of users across the main roles (admin, itil, etc). For this, Quality Clouds only requires access to the  "user_name" and "active" fields on the sys_user table.
You can modify the ACLs which Quality Clouds sends over so that only the user_name and active fields are included in the qc_access_role role.
Find more information about how to set up your ServiceNow instance here