Well, pensieve, I'm sorry, but the person the character of Rain Man was based on, Kim Peeks, is not autistic - he has organic brain damage. Doesn't mean you can't show some of the same behaviors, just means that Dustin Hoffman knows jack about neuropsychology.
As for the Onion, as noted above, sure they make fun of autistics. They make fun of sports fans, people who hate sports, politicians, voters, nonvoters, pet owners, pets, people who don't have pets, lonely people, married people, astronauts, janitors, and anybody else I haven't listed here. If you're into astrology, their horoscope will mock you personally. In short, they really do make fun of everybody, including (especially?) themselves. If you take it personally, you are indeed far too sensitive.
_________________
Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.