Hiya!
I was there last week with my kiddo. After "toughing it out" a few days, I finally just went to the cast member at guest relations and pointed to my kid, said, "She melts down, can we get her the accommodation where her ticket waits in line for her?" And that was that. Admittedly, it probably didn't hurt that by that point we were pushing her grumpy, worn-out self in a wheelchair... but the point is, yes, Autism *most definitely* is an EXCELLENT reason to use the Guest Assistance System (they'll refer to it as Gas... which is funny. "Hi, my daughter has gas, can we come back later?")
You don't have to tell them a diagnosis, just what you need. All I told them was that she melts down, which is a GREAT reason to NOT put her in a 2 hour line. Everyone was great about it, though a few of the scanners (which look like cellphones) had trouble reading through the cases, which can be a trigger for a guest who is already at their threshold. My parents brought my niece along--she is an extra-spicy Aspie, very easy to set off-- and chose not to get the GAS, for reasons I do not know... our group has a LOT better time than theirs, being able to take breaks and come back when the kiddo was ready. Fastpass is great, but you only get the one-hour return window. GAS means you can leave for hours, take a nap, get a meal, hit the pool, whatever, and come back later in the day when they're ready.[/QUOTJust an FYI the pass is called the
DAS