I agree. The author is trying to make an issue of it. I think he's overreaching. Mormonism is nutty and not Christian, but the OT/NT terminology predates mormonism and has nothing to do with it. The author should (IMO) remove that bit. It's nonsense.
Boogieman: Im pretty sure the author is Jewish, in case you didnt catch that.
In the portions excerpted, the author identifies himself as a Catholic convert, the son of a Baptist minister. FWIW, I took his "Old Testament" comment as saying that the Mormons themselves consider the whole of the Holy Bible (Old and New Testaments) as an "Old" Testament. The Book of Mormon bills itself as "Another Testament of Jesus Christ".
My reading was that the Mormons refer to the entire Bible - both OT and NT - as the Old Testament. Am I missing something?