I think it's extremely cool though and really a great idea but I am cautious about saying he has the equivalent of those undergraduate degrees.
This is the stupid, broken part of school, that only exists as a cost-cutting measure. Real learning and creativity doesn't have this nonsense. It's like saying that living in a nice house is bad because you don't get to smell your poop while you eat. No one needs that. Diego is getting a better education because it isn't being arbitrarily cut short and of track before the going gets good.
Various colleges (ex: Reed, Brown) in the U.S. don't have grades. Their graduates do just fine, afaik.
In defense of grades, they are a good extrinsic motivator for learning boring subjects. Grades are a good consequence for phoning in it. I would probably have skipped reading most of the books I was assigned to read in school if there were no consequences, and would have ended up an (even) less educated person if not for grades.