Just a wild guess, but I'm wondering if this is what makes the new process legal, or at least makes Universal's attorneys believe that is (since it hasn't been litigated). Everyone, regardless of disability, is welcome to come to the park and A: Wait in the mainstreamed standard queues or B: Purchase an Express Pass. Accommodations such as waiting outside the mainstreamed queues would theoretically be considered "better" rather than "equal" access. I am NOT a lawyer, and not taking a position on this either way, just wondering if that's where the justification for the process is coming from.
Also not a lawyer....
Looking at your conjecture, I can see the first half as a maybe - that everyone has the ability to enter the park spontaneously (albeit might not get the accommodation if so), and has opportunity to buy an express pass.
However, characterizing the accommodation as a "better" access is inaccurate. Those who are using it need it just to gain ACCESS to an attraction. Case in point:
*Even with the AAP, not all attractions at all times are accessible. My most recent trip, I got a return time for the Mummy when the standby was 90 minutes. After my wait, I went back to ride. The standy by that time had jumped to 120 minutes, meaning express wait was estimated at 60 minutes - I can't do that long of a wait in a queue environment, so I couldn't ride. So, I waited c 90 minutes to not get to ride an attraction. If I had ridden, my wait time with AAP would have been c 150 minutes total, which was almost double the amount of standby at the time I could theoretically have ridden without it, and also longer than the current 120 minute wait that was posted. This is
not "better" access, and in this case also provided me with
no access.
*I used an AAP my most recent trip, but didn't have one my first time at UO as I didn't know about it's existence. My difficulty with the lines is not the actual wait time, but the design and environment of the queue. Depending on the circumstances, I can wait a very long time (if free of adverse sensory input), or almost no time needing to exit immediately. Most waiting environments fall somewhere in between. UO designs and controls the ride queues. They could design ones that provide me access to the attraction (similar to how they have re-designed queues for physical disabilities), but instead choose ones with theming and environments that add to the sensory overload, preventing me from being able to ride because I can't maneuver through the queues.
I'm a huge Harry Potter fan. My first trip I never got to ride Hagrid's - the line wait time never went down far enough for me to attempt it without knowing the queue environment ahead of time. A handful of other rides I managed to catch at really low wait times (basically walk-on), but realized I would
not have been able to do these in that queue environment if wait times were longer and would have been one and done's if not for now having the AAP. The AAP gives me ACCESS to attractions that I otherwise would not have most of the time. My 2nd trip was much better because I did not have to worry as much about stalking the app for rides I could actually 'do' with the current wait time, and I was finally able to experience Hagrid's! Still, there were things I could not do or ride (Mummy) even with the AAP.
Please don't characterize the AAP as being a "better" experience than that of others. Doing so helps to add stigma to those who need it just to gain access. It also incentivizes people to try to cheat the system to get it and encourages others to judge those who need it.