Claims that no autistic people do X are generally false, for all X.
The key is that each of the symptoms people have mentioned are signs that a child might be autistic. If a child points to show things off, that’s a
non-autistic behaviour, indicating that the child is aware that other people don’t know everything he knows, and might have an interest in something he can
see. It’s one of the earliest autism-specific indicator I’ve heard of, but as with all the other signs, it’s not a diagnosis in itself.
I’ve also met a fair amount of people diagnosed with Asperger’s syndrome who strictly speaking meet the criteria for Autistic “Disorder”. (For some reason they avoided Asperger’s completely with me when trying not to “label” me, and stuck with PDD-NOS. But I could easily see them having gone with Asperger’s if they’d been different doctors.)