Limit Read Access to Source Control

Are folks sure that we can not restrict read access to some user roles in RTC? Is this something we might be able to customize or is there some type of work-around so that we can restrict read access to certain streams for certain roles. We are an asca-certified system and I have been told to remove my RTC controlled source control because of this issue. I am not happy as I think RTC is a fantastic source control system. I just wish it had this feature.