I tried to ask the following question, but unfortunately Mary Louise Hart ended the question-and-answer session before I got the chance:
"In the Laws, the Athenian Stranger suggest using Egyptian Laws for music, but to use them in order to celebrate Dionysus with a chorus. Does Plato's schema alter the civic Hellenic culture of choruses by incorporating the Egyptian rhythms and musical modes (which were different than the Greek choruses) into the musical and military education?"At the end of the conference during the wine and cheese social, I managed to find her and ask her this question. Gratifyingly, she told me that it was a good question. She explained that at the time that Plato was writing, the art of dithyramb was changing. This change involved the incorporation of new rhythms and modes and came to be called New Music. She explained that the regulation with the unchanging Egyptian rhythms would be a way to strain out the new experimental influence.
This may indeed have been the case. However, it brings up two new questions. First, if this is true, it might call into question Zuckert's dramatic timeline for Plato's dialogues. I say might because I am not sure whether the introduction of New Music happened in around 450 (Zuckert's hypothesis for when the Laws took place.). On the other hand, I cannot seem to find much on New Music at all, so this might not throw off the timeline.  Second, if Herodotus, who I strongly believe that Plato would have read for reasons that I can substantiate at some other time, pointed out the connection between Egypt and chorality, could Plato have been trying to make another point, rather than just considering the rigidity of Egyptian rhythms, with the references to the system?
- If you have any ideas for articles about New Music, please comment or email me.