I heard an interesting interview w/him one day. He has a special needs son and is trying to get people to stop using the word retarded...even as a joke aboout someone. I guess it's the next in line for becoming an un-PC word.
It's been un-PC for a while now. The problem is, even professionals within the fields can't agree on the proper terminology. Some people prefer alternative terms such as "intellectual disability," but I was recently facilitating a committee that reviews educational materials for fairness and freedom from bias, and they raised the question whether or not the term "disability" is acceptable. Some people don't like it, but within the field of special education, terms like "learning disabled," "emotional disability," and "visually impaired" or "hearing impaired" are still used all the time. The term "mental retardation" is still widely used within the field, but at the same time, it's not really polite to refer to someone as "retarded." You can, however, talk about someone "with mental retardation."
Here's a relevant example of the "euphamism treadmill" from wikipedia:
lame → crippled → handicapped → disabled → physically challenged → differently abled
Euphemism - Wikipedia, the free encyclopedia