The LDS canon is only as unhistorical and problematic as the Bible, and the only people who think the Bible is more legitimate than LDS scripture in terms of history have not come to grips with the historical tenuousness of their literature. ...A story about Moses composed in the Iron Age is no more factually verifiable than one composed in 1830.
It may not make sense to read the Bible and think we are hearing the voice of Moses but we are definitely hearing voices from the distant past. The world of which those voices speak is not an invention of a modern imagination. It's the actual ancient world from which our own is descended. We care what it says the way we care what our grandparents say, even if we don't always believe them. We value its stories even when they are lame, the way we value antiques that don't work.
So isn't it an exaggeration to say that the Bible is just as unhistorical as the Book of Mormon? Sure, the two Scriptures have the same Boolean value of zero for the bit of whether their fundamentalist reading is right, but you are urging Muhlstein not to read Scripture as a fundamentalist. Aren't you kind of downplaying the letdown involved in giving up the ancient status of the Book of Mormon?
The fundamentalist concept of inerrant revelation is only one end of the spectrum of ways to revere a special book, but rightly or wrongly I think pretty much everyone on that spectrum cares about provenance. The special book might not have to be ancient to be revered; perhaps an account of a vision by a revered modern figure like Abraham Lincoln would be an acceptable Scripture. Imagine how fast the value of Lincoln's vision would drop if it turned out not to be by Lincoln at all, though. Who cares what nonsense Andrew Johnson dreamed up?
Joseph Smith looks less like a Lincoln than ever these days, so an ancient Book of Mormon is hard to give up. If instead of its witness statements every Book of Mormon had had a foreword by Joseph Smith saying, "I made up this story but I think it's from God, so I hope you'll let me marry your wives," would there be any Mormons?