This is a tough one for me.....
As the parent of an autistic child, I feel like families should receive every courtesy possible when they do muster the will to undertake this type of family outing.
As an attorney, it does seem a little difficult to draw definite boundaries around "has trouble waiting in line" as a disability. Disney COULD ask to see a copy of the child's Individualized Education Program (IEP), but then you get into all sorts of privacy issues (i.e., would Disney even accept the responsibility of guarding this type of information).
Timing could not have been worse (or better - well played, Plaintiff's Attorney!) for Disney given this recent article, where Pulitzer Prize winner Ron Suskind credits Disney films as the foundation of his son's improving development:http://www.nytimes.com/2014/03/09/magazine/reaching-my-autistic-son-through-disney.html?_r=0