The message regarding the Wordpress admin being locked is actually our effort to protect you as without this, these attacks cause either your password to become compromised, or the servers to become overloaded due to the severity of the attacks.
Your best protection against your Wordpress admin becoming locked is to block based on IP within your .htaccess file. If you are blocking based on referrer, it can still become blocked depending on how the attack comes in. The following article will assist you in locking down your Wordpress site based on IP:
Lock down WordPress admin login with .htaccess