There is no mention of the fact that approximately 50% of persons with autism disorders have intellectual disabilities according to the World Health Organization, have intellectual disability. The San Jose Mercury News article does go on to acknowledge that some persons with autism may also suffer from profound "retardation" but downplays it by going on in the same sentence goes to state some also have savant abilities.:
"Autism comes in many forms. It can be a devastating diagnosis with profound retardation. But people can also have exceptional skills or talents, known as "savant" abilities."
The Stanford School of Medicine report on the study wasn't any better in  so far as it describes the study as  involving only high functioning autistic subjects but makes no mention of the 50% with autism AND intellectual disability. It generalizes the results to persons with autism and while it does refers to deficits in autism it refers only to social communication deficits, repetitive behaviors and restricted interests. The article makes no mention of the intellectual disability which restricts the lives of approximately 50% of persons with autism disorders:
"Children with autism and average IQs consistently demonstrated superior math skills compared with nonautistic children in the same IQ range, according to a study by researchers at the Stanford University School of Medicine and Lucile Packard Children’s Hospital.
There appears to be a unique pattern of brain organization that underlies superior problem-solving abilities in children with autism,” said Vinod Menon, PhD, professor of psychiatry and behavioral sciences and a member of the Child Health Research Institute at Packard Children's.

The autistic children’s enhanced math abilities were tied to patterns of activation in a particular area of their brains — an area normally associated with recognizing faces and visual objects.

Menon is senior author of the study, published online Aug. 17 in Biological Psychiatry. Postdoctoral scholar Teresa luculano, PhD, is the lead author.

Children with autism have difficulty with social interactions, especially interpreting nonverbal cues in face-to-face conversations. They often engage in repetitive behaviors and have a restricted range of interests.

But in addition to such deficits, children with autism sometimes exhibit exceptional skills or talents, known as savant abilities. For example, some can instantly recall the day of the week of any calendar date within a particular range of years — for example, that May 21, 1982, was a Friday. And some display superior mathematical skills. "

The research team is now gathering data from a larger group of children with autism to learn more about individual differences in their mathematical abilities. Menon emphasized that not all children with autism have superior math abilities, and that understanding the neural basis of variations in problem-solving abilities is an important topic for future research."