I don't really think a union would help.
What is needed is more funding and legislation to help adults with a disability, period. I think the federal government are the only ones who actually comply with the ADA law. Other companies mostly just run over it, oblivious to the law (or, even worse, just simply not caring).
It's not so much about "Don't cure me" than it is "Educate the world so that the damn draw bridge comes does already", meaning more supports for those transitioning from high school to the adult world (re: employment, college, relationships, managing one's health, general overall lifeskills) and educating people (which is easier typed than done!).
Autistic adults are in the shadows when it comes to support and resources are far and between. Worrying about a cure for autism will not help those living in the shadow to come out of hiding. Instead, it may force them even deeper into hiding their autism because they want to avoid any controversy at all! I hate the ideas and connotations people attach to the word "disability" more so than I detest the connotations associated with autism. Meaning, I don't like the pity and I don't like the head pats. I'm out in the open and if that means you won't hire me because I have a disability, well pity on you!
You almost have to go the round-about way before people will even get the message. You cannot go in with horns blasting. That will just only create more chaos and confusion. Best to slightly nudge people into the idea or otherwise you have nothing at all.
Just my two cents.
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"Two roads diverged in a wood, and I?
I took the one less traveled by,
And that has made all the difference." Robert Frost