My first impression is that the index.php was supposed to do a bit more than deleting a comment (comment/index.php) .
Having said that it seems that the only url pointing to this page is actually using action=delete, but this could be a more generic page, dealing with comments.
 
I would think that we would need: * To make this page a bit more generic, so to list comments but maybe do other things.

• Check the user right for deletion on the delete action only and not the whole page. This can for example be accessed just for listing all comments, not necessarily to delete them.