Since 0.99 and
HBASE-10336 we have our own HttpServer class that (like the counterpart in Hadoop) supports setting an ACL to allow only named users to access the web based UIs of the server processes. In secure mode we should support this as it works hand-in-hand with Kerberos authorization and the UGI class. It seems all we have to do is add a property allowing to set the ACL property as a list of users and/or groups that have access to the UIs if needed.
As an add-on, we could combine this with the read-only flag, so that some users can only access the UIs with any option to trigger, for example, splits.