There are two forms of RELEASE MLOAD command.
In the acquisition phase, cleanup is simple since no changes have actually been made to the target table.
In the application phase, the target table will have been partially updated and/or not all updates to the table will have been applied to NUSIs. At that point, it is generally better to restart the MLOAD and allow it to complete. Having a special form of the command for this case is a safeguard, to make sure you recognize the table will remain partially updated after RELEASE.