Really on the Star Wars front? I watched it and didn't give two hoots that one of the leads was black, and the existence of non-clone Storm Troopers was explained away.
In any case, if I'm to assume that this person stood up on the ride, then we have to ask if he is in the right mind. If he has some form of disability, he may not have been. Not his fault if that's the case. In that case, it's the fault of his carer for not supervising him enough. It may also be that DW is at fault for letting him on the ride, but that's another case.
If the person WAS in the right mind then they are definitely stupid and at fault.
Ultimately it comes down to who can be responsible. I could take my two-year-old son on the ride, and he understands most instructions and normally behaves himself, but he'd probably be quite excited and want to get out or stand up or something. I couldn't trust him, therefore I would be responsible and I would have to ride with him. Similar story for some people with some disabilities - the person in question could not be trusted, so there would have to be a person to take care and responsibility.