I'm skeptical that your premises are correct. But even assuming they are, for argument's sake, how does a characteristic about the extreme tails of the distribution of "ability" (arguably >3sd) translate into a meaningful comment about a gender split in chess participation closer the mean, say +1-3sd, where most players fall? You can't meaningfully infer the expected performance of the gender distribution from the tails.
Ok, which premise do you doubt?
Do you doubt that there is a difference in spatial ability between boys and girls? My understanding is that spatial ability is a reason why the strongest boys still do better in math than the strongest girls, even though girls are generally doing better in school than boys these days.
Do you doubt that spatial ability is important? My son wouldn't use the term spatial ability, but he would tell you that his ability to look 8-9 moves into a position helps him win a lot of games.
For the final part, consider the reason that Malcom Gladwell gave as to why a disproportionate number of professional soccer players are born in January, February and March in his book Outliers. His explanation was that because these were the oldest kids in their class, they were more slightly more talented than the others. They received more coaching over time, which continually increased their skill levels over their slightly less capable players. The less skilled players dropped out as competition increased, leaving a disproportionate number of players born in the first three months of the year.
