This dialogue has a sense of fresh immediacy, but we should remember that Mormon is inscribing it from Ammon’s report fourteen years later to Alma, who wrote it down at an unspecified later date. Probably Mormon had no access to official Lamanite documents, if any existed. Thus, we must consider this conversation as based on Ammon’s memory, not a transcription of the original exchange.
Ammon’s declaration that he wishes to live among the Lamanites is tantamount to becoming Lamanite. Without some assurance that Ammon had no ulterior motive—as spy for a Nephite army, for example—the king probably would not take this declaration at face value.