That's because there's nothing to fix. Nothing more than there is in a person who is left-handed. Autism is simply a different way the brain is wired, just as left-handedness is. The only difference is that autism affects a different part of the brain.

Autistic people are already burdened by their lacking so people around them should be more understanding for their sake.

The girl's action is excusable, it's those snide comments from others that are not. And why the heck does the surrounding people who heard her say "ew" be so sensitive? They weren't the ones who were criticized and anyway for a young girl to say that, it isn't a big matter to be angry about.