Of course there aren't. You can trivially imagine programming a computer to print, "2+2=5" and no verbal argument will persuade it to give the correct answer -
You can't persuade rocks either. Don't you think this might be just a wee bit of a strawman of the views of people who believe in universally compelling arguments?
There seems to be a widespread impression that the metaethics sequence was not very successful as an explanation of Eliezer Yudkowsky's views. It even says so on the wiki. And frankly, I'm puzzled by this... hence the "apparently" in this post's title. When I read the metaethics sequence, it seemed to make perfect sense to me. I can think of a couple things that may have made me different from the average OB/LW reader in this regard: