Why login url in 404 is ‘#’

In my site when using wps-hide-login plugin if i opened 404 page the login url in that page will be only ‘#’

after deep looking in the plugin code i found that there’s condition to do that in wps-hide-login/classes/plugin.php#687

/**
	 *
	 * Update url redirect : wp-admin/options.php
	 *
	 * @param $login_url
	 * @param $redirect
	 * @param $force_reauth
	 *
	 * @return string
	 */
	public function login_url( $login_url, $redirect, $force_reauth ) {
		if ( is_404() ) {
			return '#';
		}

		if ( $force_reauth === false ) {
			return $login_url;
		}

		if ( empty( $redirect ) ) {
			return $login_url;
		}

		$redirect = explode( '?', $redirect );

		if ( $redirect[0] === admin_url( 'options.php' ) ) {
			$login_url = admin_url();
		}

		return $login_url;
	}

but i am wondering why ? why not just leave the login url as it in 404 page?