No, he doesn't
Niko whatever his name is allegedly "spent time" (what, half an afternoon?) with autistic kids and a child psychologist to "understand" how they act.
Well, maybe he did - but it certainly didn't help him to act the same way.
One reviewer here states "...plays the autistic boy so well you almost thought he wasn't acting" - er, excuse me, but bullsh!t. Actually, he plays the part so badly you actually see someone acting the part. "S-p-e-a-k s-l-o-w-l-y n-o-w, r-e-m-e-m-b-e-r y-o-u a-r-e r-e-t-a-r-d-e-d" - gaah, it's embarassing to watch. That, and the eyes rolled back... squirm city.