The intro text for the Hide Backend Module clearly states:
Hides the login page (wp-login.php, wp-admin, admin and login) making it harder to find by automated attacks and making it easier for users unfamiliar with the WordPress platform.
So it will be hidden for botnets which automatically try to login using standard admin login URLs.
If you don’t want the hidden slug to appear on your frontend website simply remove the link from the active theme. However this is only an option if you don’t offer visitors the option to register (and thus login).
Anyway Hide Backend is specifically designed to prevent automated brute force attacks using the default WordPress login page slugs.