This lawsuit isn't going to go anywhere. It's not discrimination, it's safety.
Universal isn't the first big theme park that's been sued for the same issue. If the reason this person is suing for was a valid one, then EVERY ride on property would have to be accessible to people of all height and dimensions. Universal might not be the most customer friendly when it comes to most situations, but having been to both of their parks with someone in a wheelchair, both parks are suitably ADA compliant.