“Obviously, not a Bible scholar. Paul wrote in the period BEFORE 70 AD. He was dead by the end of the first century.”
I stopped at the same passage. I think what they mean is they would be our earliest copies. Paul died about 65 A.D. But our earliest copies of his epistles date to the mid-second century—almost certainly copies of copies. (There is a fragment of the Gospel of John that is about 115 A.D. and it is the earliest known new testament document.) So if the plates can be reliably dated to the fall of Jerusalem, they would be the earliest known documents, even though written later than the epistles.
While I would like to believe that they meant the earliest copies, I think the wording is more insidious, to deliberately mislead the uninformed that there was something before Paul's writings that render his false.