The normal tendency in the editing of the text has been to replace which with who whenever the referent for which is a person. In this instance, the earliest extant text (here the printer’s manuscript) reads who, but the 1830 compositor accidentally set which, perhaps because he had become used to setting which for persons (in accord with the biblical style). The 1837 edition restored the who here, either by reference to 𝓟 or in accord with Joseph Smith’s typical replacement of which with who for that edition (providing the which referred to a person).
There are clear examples of the relative pronoun who in the original text, even though which dominates. As an example of this variation, consider the following example from this same chapter:
Consequently, we let the earliest textual sources determine in each instance whether the relative pronoun should be who or which. Here in 2 Nephi 9:45, the earliest extant reading is who. For further discussion, see under which in volume 3.
Summary: Maintain the relative pronoun who in 2 Nephi 9:45 since the earliest textual source (the printer’s manuscript) reads this way.