While Googling around for other writings on changelings and autism, I found quite a few old posts from other bloggers who've picked up on the changeling rhetoric marshaled by those who see autism as an epidemic to be cured, rather than as an example of astonishing human diversity. The difference is, they managed to find explicit invocations of the changeling myth, while I've just been glimpsing it between the lines.
Here are the posts:
Two from Kristina Chew of Autism Vox, dealing with Cure Autism Now founder Portia Iverson's book Strange Son: Two Mothers, Two Sons, and a Quest to Unlock the Hidden World of Autism.
There's also this post from Ballastexistenz, with links to three posts on an older blog of hers, all dealing with rhetoric used by non-autistic autism advocates, including Cure Autism Now. Unfortunately, those links appear to be dead. The posts can be found here, here and here, though.
She also has an entire category for examples of changeling stereotypes on her old blog; she cites The Siege, which my mom actually used to own, but which I never read, and Let Me Hear Your Voice as employing changeling rhetoric. So now I guess I need to track those books down.