A new chapter begins at this point in the Book of Mormon insertion of Isaiah chapters, and it corresponds to the second major section of Isaiah. The previous unit very clearly dealt with Assyria, which was the current threat during Isaiah’s lifetime. This chapter begins by discussing Babylon, which should be an anachronism.
The Book of Mormon has already cited passages from what scholars call Deutero-Isaiah, and second Isaiah. It is posited as a different writer, whose writings were ascribed to Isaiah. Although there are other reasons for that assignation, one of the reasons is that the text refers so clearly to the Babylonian captivity, which is a hundred years in Isaiah’s future.
It is possible to suggest that prophetic knowledge is sufficient to see what will happen and identify correctly the nations by name, but this reference to Babylon occurs in a section that is attributed to Isaiah himself. How is it that this first Isaiah might refer to Babylon if the reference to Babylon is one of the reasons that Deutero-Isaiah is suggested as being a different writer?
A non-Latter-day Saint scholar suggests that we are seeing some later editorial changes in Isaiah’s text, changes which update information that pertained to the Assyrian invasion to the later Babylonian invasion which paralleled the Assyrian invasion in many ways. With the understanding that there are times when we can see a later editorial hand making some changes in the uncontested Isaiah, perhaps that lays a foundation for understanding a later editorial hand, perhaps even a heavy editorial hand, in the Deutero-Isaiah chapters.
That would allow the texts cited in the Book of Mormon to have been part of Isaiah, but simply preserved in the forms and contexts of the later editorial hand.