You should be offended, and PETA has been doing this forever to make people think eating animal or animal products is bad. But their assertion also implies autism is a negative thing, which is untrue.
You are absolutely right to be offended. I have neurodivergent people in my family. I love them dearly. I wouldn't want them to be any different. My father (likely) had autism. He was a professor who got invited to lecture at the Sorbonne and wrote something like 30 books. My brother has autism. He makes far more money than I do because he's a really good coder and he's happily married. Neurodivergent people can live lives as full of success and happiness (and lack of success and unhappiness) as anyone else. They just do it differently.
Acting like autism is some sort of horror that parents should fear is disgusting.
On my way to work, there's a house I always pass with an "autistic child" sign, a yellow square sign, next to the road. I just feel offended seeing it. Even if the individual in question could be low functioning, inattentive, actually at risk of walking into the street or something, that sign has probably been there past their childhood into adulthood, and a sign to announce your child's autism to drivers is just... something else.
it's ironic because arguably society "causes" autism, if society wasn't so fucked then things like autism and ADHD would just be quirks to take into account.
"oh yeah mary doesn't like speaking to strangers so we tend to hang out together so it's easier for her"