I always thought the music in the Plagueis scene was diagetic, coming from whatever the hell that Cirque du Soleil thing Anakin and Palpatine are watching. I guess it could still be a reference, but I’ve never read that as being “Plagueis’s Theme” or anything like that.
As a former film student, thank you. I got a bit of a kick out of you using the term diegetic like it ain’t no thang.