This is broken in so many ways. Of course the music listened to by the largest number of people is going to correlate to a more average SAT score. The children that regularly listen to classical are those with parents who either intentionally expose them to it at home (which means that they are likely well-educated) or have them take music lessons (which indicates both a concern for their child's mental development as well as above-average financial status). So music and SAT scores are largely influenced by the same factors: education and money.

Also, as someone who spent over a decade of my childhood playing classical piano, I'd suggest that the vast majority of college-age kids who have Beethoven on their "favorite music" list are smart kids just trying to appear to be even smarter. Notice how no other composers, modern or classical, are listed; Beethoven is to classical music what the Beatles are to classic rock and Jay-Z is to hip hop: a generic name for someone to pull, the Java of composers. If I was listing what instrumental music I do listen to, I'd be putting up names that define the styles I like. Philip Glass? Branford Marsalis? Ludovico Einaudi? Sure. Beethoven? Negative.

The only thing I can possibly attest to is the lyrical / instrumental dichotomy. Sometimes it takes a certain kind of mind to appreciate some instrumental music; you have to be able to sit and analyze it, recognize the patterns / progressions, etc. That's why I could see popular bands like Radiohead, U2, and even RATM to a certain extent, doing better than other groups in their genre.