How many "pioneering mathematicians" are not one-percenters? If the answer is "99%", then there's no bias in favor of those who do well on the SAT. The article doesn't give that information.
A similar question can be asked of famous musicians.
How does Lady Gaga's success support, much less confirm, your pet theory? Did she have success in a STEM field? I see no mention of STEM in her Wikipedia biography. The article points out that while the original evaluation was based a math assessment, "[l]ater, researchers included the verbal portion and other assessments", so perhaps she was a one-percenter in verbal, not math.
From her bio, she put a lot of work into the arts. That would suggest a different possibility, which is that someone who has a good grasp of any subject would also excel in other favorite activities.