Comments do not respect display_name setting, how to make plugin to overcome this

This code does the job with a filter. Doesn’t care what the comment says the author’s name is.

Nothing particularly tricky about it. Should be self-explanatory.

add_filter('get_comment_author', 'wpse31694_comment_author_display_name');
function wpse31694_comment_author_display_name($author) {
    global $comment;
    if (!empty($comment->user_id)){
        $user=get_userdata($comment->user_id);
        $author=$user->display_name;    
    }

    return $author;
}