My son is autistic and I can tell you that there is no way that we would allow this type of behaviour to continue. Having an autistic child is no excuse for not parenting your child. Had this been my child and by some chance he had wandered outside without my noticing, I would have been out the door and dealing with him as soon as I was told that he was doing this!
This exactly.
DH and I parent by a very simple philosophy: Prepare the child for the road, not the road for the child.
The rest of the world is not going to change just because he has autism so he is going to have to learn, to the best of his abilities, how to work within the boundaries of our society and that means conforming to our society's rules of proper behaviour.