Here “of no more” is a prepositional phrase that ends in a nominal more rather than in an adjectival more followed by an explicit noun (such as more people). 𝓞 is not extant for the words immediately following no more; but based on the length of the lacuna, some kind of supralinear insertion would have been required in 𝓞 if there had been a noun after more. 𝓟, the copy of 𝓞, reads “of no more”, as do all the printed editions. Since this unusual reading can be understood, the critical text will maintain it.
Summary: Accept in Alma 39:13 the invariant reading of all the extant textual sources, “the hearts of no more”; the expected noun after more (which would have had the meaning ‘people’) is left unexpressed.