We really don't know if the park is not being consistent.The easiest: we really do not know if the person in question is being honest about being on the ride before. I know that parks I visit often during the year the ride ops get to know me by face. Given this person's unfortunate condition, he would be even more recognizable.
I have no way of understanding his frustration given how capable he is, but to be consistent, certain criteria needs to be met. He does not.
This is an issue that will never go away. Ride manufacturers cannot design rides for every handicap and still ma I wish they could
With me, there was no consistancy. One time I can ride Delerium, next time not. Another visit I can, yet another, I am told no.
Delirium is a tricky ride. If you are tall or have wide shoulders, the restraint might not go down far enough for the computer to register it as locked. Hope this piece of information helped.