many (most?) autistic children may NOT be able to totally overcome their profound neurological differences to fit into a neurotypical ideal that many non-autistic children struggle with
However, if no-one tries to teach them what is appropriate, then they never WILL be able to overcome their profound neurological differences, will they?
Allowing ANY child to behave in a potentially dangerous manner, particularly around smaller, younger or in any other way, are vulnerable children is NOT GOOD PARENTING.
Any child can slip out of sight for a moment and create havoc - none of us have eyes in the backs of our heads - but abdicating parental responsibility because your child has greater difficulties than may others isn't on.
This boy could have badly hurt a three-year-old child. His parents should have at least apologised, even if they felt it appropriate to mention his autism then.
Had it been him that was hurt or frightened (e.g. had he tried to push past much bigger children, and ended up getting shoved out of the way himself) would his mother have been happy for him to be upset/hurt/frightened?
If not, then his parents should make sure he doesn't upset/hurt/frighten other children.