What is the impact of Removing DBA_ROLES privilage from SELECT_CATALOG_ROLE and CTXSYS

KPMG auditors were pointed out the DBA_ROLES privileges granted to SELECT_CATALOG_ROLE and CTXSYS have to be removed from production 10g databases. So Id like to know the impact of removing these privilege? 

KPMG comment :

Prevent access to DBA_ROLES from unnecessary users

Medium

It was observed that the following users have given access to the DBA_ROLES "CTXSYS" "SELECT_CATALOG_ROLE"

DBA_ROLES lists all roles that exist in the database. It should only be accessed by the SYS and the database administrator

Allowing access to DBA ROLES table to an unnecessary user may enable that user to alter the DBA_ROLES table, which may result in privilege escalation or system instability