I will admit I can get little or nothing out of Menexenus other than Plato making the point that statesmen often make horrifically tedious speeches in the name of patriotism. This is true, but one doubts Plato’s genius was need to demonstrate it.
Hmm. I would have thought the point of the Menexenus is that Socrates can ape the speeches of the politician spectacularly well. And one point of doing it "spectacularly" is that the philosopher does it in such a way that the politician doesn't know he's being mocked; he thinks the philosopher is doing a dull impression of the politician. What he doesn't realize is that the philosopher is giving an accurate impression of the politician, which the politician takes to be dull. The dullness of the politician is due to his neglect of two things: justice and the divine. (Collins and Stauffer make this point in their introduction to their translation of the dialogue.)
Whether this amounts to more than what Reynolds has noticed is an open question.