The reason is because a new analysis in Moleular Autism finds that Hans Asperger, the Austrian pediatrician for whom a mild segment of the autism spectrum is named, collaborated with Nazis and helped kill disabled children.
The Third Reich’s child-euthanasia program was an extreme form of the eugenics movement promoted by the American genetics movement, lauded by people like Supreme Court Justice Oliver Wendell Holmes, who spoke for America's highest court that a rape victim should be sterilized because he believed she was simply promiscuous and she would be the “probable potential parent of socially inadequate offspring, likewise afflicted”. His beliefs were shared by luminaries of the day such as H.G. Wells and John Maynard Keynes.
The Nazis embraced eugenics, and eugenicists embraced them, because they both believe it was possible to establish a “pure” society by eliminating those deemed a “burden.” Though perhaps not a member of the Nazi political party, Dr. Asperger referred disabled children to the Am Spiegelgrund clinic in Vienna, where they were killed from 1940 to 1945.
Autism advocates and those who identify with the term "Asperger" will be concerned with the association, but it is not new, there had always been an undercurrent of doubt about him for Austrians. However, the casual users are the ones who are going to abandon it as a colloquialism.
He redeemed himself to many. He was leader in autism research, so well known that the developmental disorder he called "autistic psychopathy" in 1944 was changed Asperger syndrome after he died in 1980.