That's very specific, but possible. The interesting thing about scientific studies is that you can essentially find similar results for gluten, dairy, certain macro deficiencies or excesses (like carbohydrates, vitamins, electrolytes), etc -- if not overwhelming results for just gluten or wheat alone, especially for those who are sensitive to it.
I think the unfortunate truth is that sleeping is tough for a lot of us with ASD, but that doesn't mean that certain dietary restrictions can't help, because they absolutely can. The issue with specific ingredients is that they can just complicate the issue, IMHO. Mostly, a cleaner diet, more exercise and larger 'brushstrokes' can work wonders.
Of course, genetic testing can rule out those quirky specifics, though. I've been down those rabbit holes, and honestly none of them were true. Go figure