The singular it here in the original text acts as an existential it, not as a pronoun for the preceding none. Except for this it, the sentence is in the plural: “and none were consecrated except it were just men” (the second were is actually a subjunctive form, not a plural indicative form). In his editing for the 1837 edition, Joseph Smith replaced the existential it with the plural pronoun they, which directly refers to the preceding plural none.
There are several other examples of this existential usage in the original text, none of which have had the existential it edited to the personal pronoun they or he; moreover, in each case the existential it is followed by the subjunctive were:
In the first of these (Mosiah 6:2), it were is completed by a plural noun phrase (“little children”) and in this respect is precisely like the original reading for Mosiah 23:17. Moreover, in all these examples the main clause at the beginning contains a universal quantifier, either negative (none or not one) or positive (all ). Clearly, the original usage in Mosiah 23:17 is intended and will therefore be restored in the critical text.
Summary: Restore in Mosiah 23:17 the original use of the existential it: “and none were consecrated except it were just men”.