This verse should be read as a continuation of verse 2: “and now, after that… Christ truly had showed himself unto his people.… ” Moroni takes this reference as the Messiah’s visitation to the New World, allowing him to reflect on the sad fate of his people since that visit; they “have all dwindled in unbelief.”
This passage had begun with the information about the brother of Jared’s vision being hidden up until the right time. Now, Moroni, too, must “hide them [records and interpreters] up again in the earth.” Moroni sees the parallel between his record and that of the brother of Jared. A further parallel is the essential role of the interpreters. By now Moroni understands that he will be hiding those same interpreters for that same future purpose in connection with his father’s work.