pth, your story is interesting, but not unique. Sadly, many "master classes" run like this. However, you state several times that the audience was less than participatory, and that can make a huge difference. I paid out of pocket to have a pro come talk to my students; I was expecting some major epiphany. Instead, he conducted a listening clinic. One could argue it was self-serving, and it certainly was not what I had expected when I cut the check. But here's the bright side: The students completely dug it, participated, and told me they learned a lot about how they listened. The audience will derive from a master class what it is willing to. Some of what you describe of JC's presentation seems to have been designed to get someone to participate. If the class failed to engage, shame on them, not James.
I had another series of "master class" sessions with one of the young NYC lions. It was complete BS, and while he was working with us on arrangements and such, his **** poor attitude and flaunted arrogance really impeded the learning process. That's my opinion, others, mostly younger kids, thought he was great. Most of the adults in camp thought he was (and is) an arrogant little punk. Lots of things factor into the assessment. I, for one, would like the opportunity to have a master class with JC. Good luck to the OP, and I hope you get as much out of it as you can.