Socrates conceals his dialectic exercise with rhetoric and even eristics in an attempt to make Io, who enjoys listening to sophists (he says "you sophoi"), and consequently nice rhetorical stories such as the magnet analogy, actually consider what his rhapsodic techne is. It does include thousands of Homeric lines as subject matter, but this does not mean he is an expert (has the techne) regarding each subject talked about.
I have not speculated in the podcast, but Plato may have written this dialogue with some of his own students in mind. Plato was considered divine by many people, and Plato's Socrates emphasizes that divinely inspired authors lack intelligence. An interpreter of Plato's dialogues is like the rhapsode, probably even learning the dialogues by heart, which might make such a Platonist feel that he knows more than he really does. This dialogue may well have given such an interpreter pause for thought.
