Well, I won't sit on my hands 
My children both have autism. My youngest also has ADHD.
If they are being rude - they get told!
Autism is not a reason to allow unacceptable behaviour.
It is a reason to understand what may at times be socially inappropriate behaviour, with a view to supporting the person as far as possible to understand what is and what is not ok and to function as best they can. But you don't shrug and say well, autism, that's ok, do what you like.
You do the person a great injustice by not helping them to understand socially acceptable behaviour.
And - someone on the autistic spectrum can just be being an arse, same as anyone else.
So deal with it. complain. Ask for support for them, someone to have a word and outline acceptable behaviour.
It's what I'd want someone to do for my kids, if they were behaving in an inappropriate or unacceptable way.
(what I DO want, when they ARE!
)