It's always funny to see this kind of selective deference accorded to biology. Though there is no mention of an adult control group in this "study", I guess we are to extrapolate that one group (children) has neurological advantages over another (adults), even as we are enjoined from noting even the possibility of similar neurological differences between any other two groups (such as 20 year old programmers and 40 year old programmers...or geniuses and neurotypicals).

Hard to predict when and how a true egalitarian will allow for biological constraints on their ambitions.

I don't quite follow you... Do you doubt that there are significant neurological differences between children and adults that enable children to perform feats (involving neural plasticity and learning ability) that are out of reach of adults?

Of course there are. But I gather you doubt that there is significant variation in intelligence in the population at large, due to factors just as biological as those leading to the child/adult differential. That is the purpose of all this 10000 hours stuff: to deny that some people can't learn some things.