Soup from the carcass is delicious, but there isn't time to do that during the meal. Even with a pressure cooker it's going to take at least an hour. (And if several tables order the same dish, you're gonna have a bunch of pressure cookers in your kitchen.)
So... the idea is sound, but I'm doubtful that they actually do it the way they claim. Which would make sense with the "hero chicken" story they admit to.
If they're also using the original poaching stock I could imagine you'll get a pretty stock even in 30 minutes. You'd still need to cook anything else you wanted in your soup -- vegetables, pasta -- though there are tricks for par-cooking these.
I don't own a pressure cooker, so I'm only reporting what I've read. And they do say that a pressure cooker makes better stock in shorter time -- there are things that not even a 10 hour simmer will get since the temperature never gets high enough to dissolve some things. Still, 30 minutes sounds sub-optimal, and I wouldn't expect anything to be even the slighest bit sub-optimal when you're paying two-Michelin-star prices.
And yeah, best read is they already had fully done stock and just add these bones to that and drain off some for you to have. Leaving it in to continue to make more stock.
And entertainment is full of evidence that people don't need or want to see the full process. For example, good editing can make a movie. There is still a market for stage plays, of course. There is always a curtain, though.
And fair that there could be a market for this. Dozens of people, even. My point is that the market is almost certainly as much a stated market as it is an actual one. People want to be somewhat entertained, sure. And they want a good meal. Seeing the exact chicken that they are about to eat as it makes its way through the kitchen feels unlikely to be a deciding factor.