In my early years, I worked at the Alabama Space And Rocket Center (now known simply as The Space Center). I operated a ride called the Lunar Odyssey. A centrifuge ride, that exerted approximately 3.2 G's for roughly 7 1/2 minutes. It accellerated slowly, and decellerated in about the same space of time. We had more than one person ask to get off in order to blow chow, but no one on my watch ever croaked.
We had an extensive laundry list of medical conditions that we had to loudly recite, and hush the patrons to make sure everyone got the message. I can't imagine that WDW would gloss over precautions like that, and I doubt they do.
The thing is, people have to take personal responsibility for their own well being and set aside their enthusiasm if it obviously puts them in peril!!!. Otherwise, God and Darwin will shake hands, and cull said twit from the gene pool.
Yeah, it's unfortunate. Yeah, undiagnosed conditions will sneak through. I'm not trying to be an insensitive @ss about this. But bad things happen. The majority are avoidable, however.
OK, somebody else can have my soapbox now.