I've just released Protector 3.13 with anti auto registering bots.
(You can search it by email@example.com , george-walker-bush.info or firstname.lastname@example.org)
If you installed Protector correctly, just copy the plugin filters_disabled/postcommon_register_insert_js_check.php into filters_enabled/.
No core hacks needed.
You should check a guest can register after enable the plugin.
If you access via "Reliable IPs" in Preferences of Protector, this plugin never stop registering.