The 1907 LDS vest-pocket edition has the plural men instead of the singular man. The use of man here means ‘mankind’, which nonetheless has a plural referent as shown by the plural pronoun they in the following main clause. There are other examples of the singular man taking a plural pronoun. The following example is one that has never been edited:
Summary: Retain in 2 Nephi 9:6 the singular man and its plural pronoun they.