Textual: Mormon is now copying the speech from the Limhite records.
While it is possible that Mormon created dialogue, it is less likely than his creation of the narrative portions. In this particular case, the nature of the discourse suggests that it is authentic to the period. Rather than a terse introduction of the topic, Gideon gives an elaborate introduction to the reason why he should be granted the ability to speak. He reminds the king that his advice has been valuable in the past, and that in recognition of past service he should be heard.
Of course Gideon's service would be quite well known to Limhi, and all of Gideon's introduction entirely useless from an information standpoint. However, this is a formal situation, and Gideon is seeking formal audience before his king and in front of the population. This requires the protocol that Gideon exhibits. Mormon's style tends to be more terse, and had Mormon invented this speech it would be more likely to follow Mormon's desires to keep the text simple and to the point.