Name: Real wp-comments-post.php
Version: 1.1
Description: Denies any POST attempt made to a non-existing wp-comments-post.php..
Rules: 
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ %relative_root%.*/wp-comments-post\.php.*\ HTTP/ [NC]
RewriteRule .* - [F,NS,L]