The mention of Jarrett in the article is what led to me asking throughout the article, "But what about musicians who are famously accomplished at both?!" They quoted Jarrett but didn't really expand on it, other than to use it as an argument from authority in support of what they think their study means about how the brains of musicians work.

The study included people who aren't at all like Jarrett (they are either/or musicians, while Jarrett is a both and then some musician), so the quote felt vaguely forced into place.