In my opinion there is no backbone at all.
This website, while interesting, is comparing the Book of Mormon which has had only spelling and grammar changes made to it to the Bible which has been written, copied, translated, copied some more, and after many stages of this we are digging into whatever copies we have available and using that as the standard for how The Book of Mormon should be?
Apples to Oranges here, but yes it is interesting and fun to look at.
I think Hantler's is asking why translation errors in the KJV also made there way into the BofM. I don't find that troublesome at all as the passages in question were translated to meet the known scripture of the day. The belief in modern interpretation takes care of the errors, just as the Catholics now update their bible to reflect the most up-to-date corrections.