I thought that it was much more interesting that they had hardly any data for students with a SAT-m under 600, which makes the conclusions slightly less convinc

I thought that it was much more interesting that they had hardly any data for students with a SAT-m under 600, which makes the conclusions slightly less convincing. That said, there is a clear wall in the data they have so far. It would definitely be interesting to look into this further and see if that is the case, and also investigate more fields (I didn't see anywhere in the paper a complete listing of all the subjects they compared, which was a pity). I know I would not be surprised if a similar pattern was found in Computer Science!