Certainly the Messiah knew what he was looking for even before Nephi laid the scriptures before him. He did not ponder their organization or page extensively through them. He went directly to the subject which was uppermost in his mind, noted the missing material, and pointed it out. (See commentary accompanying the Helaman 13 headnote.)
The fact that he called for the records, knowing what he was looking for beforehand, reveals that his purpose was to highlight the importance of the living oracles’ record. He thus emphasized them as conceptually equivalent to Isaiah’s writings that he had so recently quoted. Not only are his own words important to record, but so are those of recent prophets like Samuel.