My Kid is a Damn Nutter

[Happy Monkey]

It sounds to me like they are saying that a symptom of autism, strong preference for routine, specifically in food choice, is causing the constipation. I doubt they'd caution against enforcing a varied diet, as opposed to a restricted one. "Not just bread and cheese" is different from "no bread or cheese". Though I do know that it can be hard to get a child to eat something else if they know that what they want is available.

Without calling out any particular restricted diet, they can be dangerous and risky (though that's an extreme case), meaning you have to be very careful when using them, not that you should never use them. Without evidence supporting a link between diet and autism, and with the possible danger of a poorly crafted restricted diet, they reccommend against.

Edit: I do wonder whether the 77-72 GI number includes the 34-18 constipation number.