I'm not going to get into the whole civil versus federal cases because the requirements can vary by state and judge.
In an at-will state, they can get around requirements by showing a single example of failure. Did you wear a sleeveless blouse? How about that report that was a day late? It doesn't really matter though because most workplaces make you sign a contract acknowledging you acceptance of at-will employment.
There is also the problem of misrepresentation on a resume. If you are unable to complete a job as given, that gives another excuse.
Quick math shows that an extra 10-minute break every day for a year equals out to 43.3 hours of work lost.
This would be a very easy case to win.
My advice would be to leave it off of the resume. Instead, if it is true, add in any activities that has been performed for autism in the community (member of non-profit, took part in 5k, speaker at an event, etc.), inform HR after hiring and do the best to not allow it to define them as an employee. I know that last bit sounds harsh, but let me explain.
If a resume comes across my desk and it points out that the candidate is a member of the local Pride chapter, I'm thrilled. It means that they are active in their community and shows an ethic I wish to encourage throughout my company. If a resume states that they are gay, well, that is a different matter. That shows me that they are using it as a qualifier and I can expect them to use that qualifier to their advantage as often as possible.
The difference defines how an employee is going to affect the entire culture of a company, which affects clients, which affects income. Are they going to be one that pushes for helping the community or are they going to use something about themselves as a qualifier for their actions? Be the great employee that has autism and not the great autistic employee.