Here in the printer’s manuscript, Oliver Cowdery inserted both have and be with heavier ink flow. These supralinear corrections were not immediate but appear to have been made when Oliver proofed 𝓟 against 𝓞. In this passage, neither the have nor the be seem necessary. For instance, we can have either “he must needs hope” or “he must needs have hope”. Similarly, for the initial reading “there cannot any hope”, any can be interpreted as meaning ‘any person’. Notice that for both initial readings, the word hope acts as a verb; in the corrected readings, the word hope acts as a noun. Generally speaking, there would have been no strong motivation to emend “he must needs hope” and “there cannot any hope”, so 𝓞 probably had the have and the be.
The use of the verb have with the noun hope is consistent with other usage in the text (see, for instance, the discussion under Jacob 5:46). In addition, here in Moroni 7 there are two other cases of “must needs have” followed by a noun:
On the other hand, we can find textual support for both the initial and corrected readings for the clause “there cannot (be) any hope”, with two examples with the verbal interpretation and one with the nominal (which has the be verb):
verbal interpretation
nominal interpretation
Summary: Accept in Moroni 7:42 Oliver Cowdery’s correction of “he must needs hope” to “he must needs have hope”; here his correction appears to be the result of proofing 𝓟 against 𝓞, just as it very likely was in the next clause when Oliver supralinearly inserted be in “there cannot be any hope”; these two corrections appear to have been made at the same time.