Lydia X. Z. Brown has an opinion piece in the Washington Post which, in my humble opinion, is well worth reading:
Here are the first two paragraphs:
When Donald Trump called Greta Thunberg “so ridiculous” and said she needed to “work on her anger management problem” and “chill,” it felt all too familiar. Like Thunberg, I am also an autistic activist used to people with more power dismissing me as angry, unmanageable and unlikable. These attacks come alongside insinuations that I never belong in the room and do not deserve the accolades I have earned.
Even when autistic people are honored, like Thunberg was when she was named Time’s Person of the Year, we are immediately discredited as children, reinforcing the ideas that children and autistic people alike have no agency and our work is illegitimate. For me, this has happened at every stage of my work as an advocate, since I drafted legislation on police training in Massachusetts when I was still in high school up to when I designed lesson plans on disability justice used in thousands of middle and high school classrooms through Amplifier’s We The Future art education project.
Lydia Brown is someone I respect a great deal. I’ve been following them for many years.
My autistic kid is lucky that advocates like Lydia are out there.
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by Matt Carey
Left Brain Right Brain 
I am very familiar with the devoicing Lydia writes about.
Because I am articulate and forceful, I am generally attacked in two ways. Firstly, my detractors claim I can’t be autistic because I am able to communicate extremely competently.
The second and far more dangerous argument they use is that I can’t represent autistics because I am able to communicate so well. It’s B.S. of course, but B.S. that’s still taken seriously by far too many. The Autism Science Foundation hosted an article by one Matthew Belmonte Ph.D arguing precisely that. I left two comments, but neither was released from moderation.
I have an understanding of the sort of silencing you speak of. Over the years I’ve been told many times about how (a) I don’t have an autistic kid or (b) my autistic kid is “high functioning” (by people who know absolutely nothing about my kid) and so my opinion doesn’t count.
There’s a strange rating system where somehow the weight of one’s opinion is related to some perceived level of disability.