The title does put 'the opposite of autism' in quotes, to make it clear it's someone's phrasing, not a matter of fact, but the body of the article quotes someone from a foundation for the disease saying:
> "There is a classic autistic profile to which Williams Syndrome is the polar opposite. People can gauge the mood of a crowd and adopt without understanding the nuances of the situation."
That, it seems to me, could be a defensible point. That is not something you'd ever say an autistic person would be good at; it's antithetical.
But more to the point, not everything is an attack on autistic people. These are people trying to make a case that people should care about and be aware of the welfare needs associated with a poorly-understood disorder (which is maybe a hundred times rarer than autism). It would be fair I think to allow them the room to explain that.