I would agree with this feature request. I have disabled the blacklist manager in favor of adding CIDR blocks directly to the .htaccess file.
Example:
* I get a lock down notification for x.x.x.x
* I do a whois x.x.x.x
* I find out the CIDR block assigned to the provider
* I block the entire CIDR block x.x.x.x/19
