This really only masks the issue that is happening here. We ideally need to implement `hook_islandora_object_purged` (https://github.com/Islandora/islandora/blob/7.x/islandora.api.php#L273) to check to see if the object is ip embargoed when a purge happens. Furthermore, we should add a new batch to the `hook_cron` or an operation to this batch here https://github.com/Islandora/islandora_ip_embargo/blob/7.x/includes/utilities.inc#L277-L280 to delete all references to no longer existing objects.