Both liberals and conservatives in this country have made a habit of overtly practicing ideology-over-facts, especially when it threatens their core values. Personally, I'm sick of it. Ideology and opinion needs to take a back seat to assertions of fact. If you are uncomfortable with data, the problem is with you. I haven't looked at this study in detail, and there is a possibility there are flaws. However, the findings don't seem that outlandish or surprising. Kids that are poorly prepared for university can't hack STEM degrees. This might not even be considered a reason to change affirmative action. Actually, it could be used to design programs that make sure affirmative action is more successful. If someone has good data, it must become part of the discussion. If you keep good data out of the discussion, no matter how distasteful it might be, you are practicing willful ignorance, -and we know what Yoda says about that.
You may recall that it took a lot of scholars a long time to pick apart Murray/Hernstein's "Bell Curve." That may have been the most peer reviewed book in the last 20 years. :-) And in the end, AFAICR, they had some issued with data analysis that was the core of the book, but mostly it stood. -XC