Internal Consistency regarding the Isaiah Chapters in 2 Nephi

The critical view of the Book of Mormon sometimes goes that Joseph Smith got to the end of his massively ambitious project and then decided to simply read from the KJV chapters of Isaiah to fill his desired word count, inadvertently exposing his entire work as a fraud by quoting Second Isaiah, which scholars have nearly unanimously concluded would not have been available to Nephi prior to the Babylonian conquest.

I admit the Isaiah chapters are hard to understand for a lot of reasons, including this reason, but there is clearly much more to the story than Joseph grabbing his Bible off the shelf at the end of his dictation process. Their purpose for being in Nephi's record speaks to major themes throughout the Book of Mormon--the remnant, the latter-day gathering and the establishment of Zion, etc.

Consider, for example, the fact that Jesus Christ references Isaiah in 3 Nephi 23:1, when he is visiting the Nephites:

1 And now, behold, I say unto you, that ye ought to search these things. Yea, a commandment I give unto you that ye search these things diligently; for great are the words of Isaiah.

By this point in the dictation, Joseph Smith has only quoted Isaiah in the words of Abinadi found in Mosiah 14 (115 chapters earlier).  The 1 Nephi and 2 Nephi Isaiah passages won't show up in the dictation for another 60-70 chapters).

What does this mean?  To me this is an indication that the presence of Isaiah's words among the Nephites must have been known to the author of the Book of Mormon from the outset and not something that was added during the process.