My autistic nephew has the memory of an elephant and would have no trouble telling his parents what happened.
You can ask the kid what happened on any date in his life and he can tell you in unbelievable detail.
You can ask him about any movie and he will tell you when it was released and who the production company was.
But he would get freaked out pretty bad if someone did something like this to him.
HOWEVER, that said, I am not making any judgement on this incident at all.
As soon as I posted this, I realized that autism runs a wide spectrum.. But regardless, the article claims the oldest doesn't say much. Just thought it odd. I suspect the parents embellished the story a bit.