A very smart former student of mine from the University of Texas, Mark Engelson, who is on the autism spectrum, writes:

I read the post you shared on the blog with great interest, and I share your doubts about ableism.

There are things that I do (at times, not at others) that can be deeply unsettling to others. My voice has a tendency to crescendo without my conscious intention, for example. This is of a piece with a particularly verbose, larger-than-life manifestation of my autism which is, to be fair, a lot. This combines with a distinct lack of grace (I can't drive, and I once broke a partner's toe when I tried folk dancing as a college freshman). As much as I might like to believe otherwise, I can very much be the bull in the proverbial china shop.

While I had some sense of this about myself, it wasn't really clear to me just how unsettling these traits are until I saw them in someone else. I had the opportunity to meet one of my heroes in music – I don't want to call anyone out – but this gentleman does the exact same thing with his voice, and his affect was like a coiled spring that had just done a line of coke. When I spoke to him, I experienced a brief moment of uncertainty in which I was afraid the guy was going to go apeshit – possibly violent – on me; he actually hugged me. While I know of no history of violence by this individual, his bearing had that effect on me.

We rely on these various signals to interpret other people's intentions, intentions which can inflict mayhem or violence on our persons. While there is diversity in the range of signals people give, the signals most people give off fall into a  broadly similar range. If they didn't, social interaction would be almost impossible. From an evolutionary perspective, we need to be able to perceive threats in order to survive; more generally, we'd be lost in epistemic limbo if we weren't able to attribute intentions to people and usually be right about it. (I suspect nonverbal communication is as much about coordination conventions as is verbal.)

Even being on the spectrum myself, I sometimes find the mannerisms, speech, affect, etc. of other autistics deeply unsettling and hard to interpret. While we can be more tolerant about behaviors like stimming, I have serious doubts that there's any way to get around affect sending up a "red flag."

He added: 

Realizing the things I have mentioned realizing about myself is, in a word, harrowing. I walk constantly on eggshells, worried about how "strange" I am coming off and whether I've made someone uncomfortable. I wonder how much of a self-fulfilling prophecy this is, with the anxiety and meta-awareness interfering with my ability to relate people  more than just acting "naturally."

While skeptical about the possibilities for accommodation, there's a bare minimum that we can do to improve. I'm still hurt by [a student in graduate school] calling me a "retard" more than 16 years ago. (I had misread a map on he way to a party [a professor] threw at the end of the semester for his students.)