Sounds to me like the school you attended, particularly the physics teachers screwed up.
The physics here are simple. The safety restraints cannot reliably hold her in the rides because she generates too much inertia.
Sounds like the ride manufacturers screwed up in physics too - as there are no weight restrictions. In the article it said she wanted more space - but they didn’t want to spare the seat. I have no idea what the ride is like, but lots of them with a bench seat just have a bar in front of all the people. One 400 pound woman would be the same as me and my brother sitting next to each other.
Now I think its stupid to have fat people get there own set of rights - but I also think its stupid for a business to piss off their customers. But - it’s their business, so they can if they want. Well - they SHOULD be able to turn away who they want.