“Whatever you call the mentally retareded will inevitably be pejorative, since it’ll never be a good thing to be retarded.”
It has to do with intent. If the intent is to hurt and insult, then yes - it’s pejorative (as would be the case with any other insult given to someone), but if the intent is to describe a condition (a chronic slow mental development/late development), the term is not pejorative. I was speaking of a time when the latter usage was still openly accepted and not viewed as inherently “insulting”. Otherwise, I agree with the rest of your post.
"In the same year, 1906, an amendment to the Political Code changed the name from the Asylum for the Deaf, Dumb and Blind, to the California Institution for the Deaf and Blind."