- what all studies show is some vague "craving" for something generic, e.g. the link between iron deficiency and craving for ice

- but what you see in autists is often a far stronger effect and not just for eating something, but also against eating most other food. A craving for chocolate does not remove appetite and willingness to eat other food. It just makes you really want to eat chocolate.

- more important the way autistic people get fixated on a monotonous diet is far more specific then any effects we have observed from gut bacteria or other similar sources AFIK. Like lets say your gut bacteria might make you crave fish. You autism on the other hand might make you crave dino formed fish sticks with a specific texture. And there is just no way gut bacteria care about your fish sticks being dino formed or the specific texture of them... But a autistic person often does care, quite a bit even.

They didn’t run any experiments trying to change the diet or microbiome. They just correlated dietary preferences with some markers that might be correlated with the microbiome.

The paper does not say anything about how changing the microbiome might change preferences. The simplest and most well tested explanation is that dietary preference are driving the microbiome.

There’s a lot of woo-woo microbiome discussion out there that misses the really obvious basics of how the microbiome comes to exist and thrive: What you eat is what the microbiome eats, so changing what you eat will change the composition of bacteria that thrive. People who prefer chocolate are correlated with people who prefer sweet diets. High sugar intake is proven to alter the microbiome.