In reality, autism can be treated only by intensive training, combined with lots of focused attention from the parents.
This is exactly what happens in these cases. Take out all the mercury thingies and all the chelation, and replace them with any placebo. It’s the training and the attention that helps these kids.
The success of chelation varies case by case, for a million different reasons. In this case a lack of glutathione (probably very bad in this case) produced a lack of results because the body could not purge mercury from within the cells. That phenomena is going to be different for everyone, but it does prove a point.