One wonders here if perhaps the word forth is missing from the end of “their cry shall go”. Elsewhere in the text, we always have forth when referring to a cry being broadcast to the people (although there are only two examples):
The original manuscript is not extant in 2 Nephi 3:20, but it seems quite plausible that it read “their cry shall go forth”. The adverb forth could have been accidentally lost when the text was copied into the printer’s manuscript.
There are two cases in the manuscripts where the adverb forth was dropped while the scribe was copying the text into the printer’s manuscript; in the first case, the error was caught, but not in the second:
Thus there is both internal and external evidence that forth is missing from 2 Nephi 3:20 and that this verse should be emended to read “their cry shall go forth even according to the simpleness of their words”.
Summary: Emend 2 Nephi 3:20 to read “their cry shall go forth” since otherwise we expect forth when referring to a cry being broadcast to the people; in addition, we have clear evidence that Oliver Cowdery sometimes dropped forth when copying into the printer’s manuscript.