True, but he entirely ignores the critical question of the weapons available for that defense.
Focusing on the fact that they didn't even try is an important part of the issue, but only a part. If all they had available to them for that fight was books, pens and calculators, then it's a bit more understandable that they didn't feel strong enough to do something. Don't get me wrong, they could have done something, and should have. But when the bad guy has a gun and you don't, it profoundly changes the psychology involved.
So, yes, I agree with the author. But he left out a major part of the discussion by ignoring the RKBA and specifically concealed-carry on college campuses. (campii?)
The students and professors had overwhelming numbers. I truly wonder if our society has contributed to the "every man for himself" attitude that seemed to have prevailed, or if Cho's attack was merely swiftly and violently executed so swiftly that people were caught that off guard. It does seem that there was at least one classroom where students barricaded the door, and that minimal use of their one advantage (i.e. strength of numbers) apparently saved more than just a few lives.