This is completely unsupported intuition, but I won't be surprised if programming especially benefits from working memory more than other aspects of intelligence. That is, it seems possible improved working memory improves programming, without improving grades or exam scores.
I think that's possible too, but I have no idea how one would study that. The empirical study of programming languages is still in its infancy - we can't even say with high confidence whether dynamic or static languages are better to work in, much less show that WM increases cause programming improvements.
