One reason for restricting the rsh-ability of some commands is a concern about potential problems due to simultaneous invocations (via multiple rsh sessions). In a few cases the command code hasn't been designed to lock everything that needs locking, and in other cases we haven't reviewed the code enough to convince ourselves that problems doesn't exist, so until these issues are resolved, we restrict rsh-ability as a simple way of limiting their use and advising people of the danger.

...Tim Thompson...Network Appliance, Inc...