But the park is the attraction. Disney is not barring anyone from entering the park, drill deeper and you can say the rides are the product, and again they aren't barring anyone and have even made modifications to accommodate various disabilities to experience the rides.
To use your comparison, I don't believe at a ticketed event, there is a waiter available to someone using a designated disabled seat to make getting concessions easier for them even though there are premium seating areas elsewhere in the arena where there is indeed wait staff provided. Nor have I ever seen a bypass line at the stands to allow someone a way to get concessions quicker, or a lane pulling into the stadium to make the wait for parking quicker or the wait in the line to get into the facility faster. That's why I think there is no legal standing for a suit.