I'm off to Chicago tonight for my thesis advisor's retirement conference, during which I will answer a whole-hearted "no."
Many children with autism grasp a variety of non-literal uses:
-Ask "Can you pass the salt," and, rather than simply answering "yes," they will pass you the salt.
-Ask "Why do you keep picking your nose," and, rather than giving you a reason, they will take your words rhetorically and stop.-Ask "are you stuck," and, rather than objecting that math isn't sticky, they will tell you whether the algebra problem has stumped them.
In their own non-literal, figurative speech, autistic people can be quite clever. Here's a recent simile from my son:
Changing passwords so people won’t guess is like hide and seek when I move while other people are trying to find me.
Many autism researchers haven't noticed these abilities, and, beginning with Alan Leslie, have proposed that an impairment in moving beyond literal meanings to higher level meta-representations is inherent to autism.
But autism, like passwords that keep changing and children who keep hiding in different places, is a moving target. Just when we think we have it within our sights, it winks at us and shifts on--sometimes to places we never thought it could go.