Yeah, except that it took a long time for the police to get there.
Contrast the VT shootings with the recent, similar horror in Salt Lake City, UT. There, the murderer was stopped quickly because there was a man with a concealed weapon in the mall to stop him!
The emerging doctrine, while a major improvement over the previous, passive one, is still lacking somewhat in its treatment of self defense. It still favors the idea that "It’s OK. It’s going to be OK. They will be here soon.", since it doesn't encourage ordinary citizens to arm themselves and take the defense of their own lives into their own hands.
Concealed carry by citizens is the only logical choice. They are on scene, and with some basic practice can make a vital difference. And yes, there will be a screwup or two - humans are involved so Murphy’s Law is in force. It’s still better than the alternative.
Correct me if I'm wrong, but I think you and the author of this piece are making exactly the same point -- and it's a really good one. Just as police are now willing to be more aggressive when needed, average individuals (mostly men) also need to recognize when it's time to actively fight back against evil.