I know you've thought of this, but encouraging you to try again. Ive found that kids will refuse something to eat and then come back to it later when they are actually hungry.
It may take a tantrum and crazy cry session, but with love and attention they can normalize and get back towards a more normal diet.
I get that kids have certain things they don't like, but for anyone whose kids only eat things that are deep fry brown, I think it's worth the short-term crisis to solve the long-term aggravation and health issues.
Edit: ok yeah I missed the potential autism part of question. Encourage other parents to stay strong with eating habits if that is not the case