I was one of the kids who could use computers. I got a lot of negative reactions from teachers whenever I used the DOS prompt for anything. Kids in high school who know programming or other advanced tricks learn quickly that the teachers finding them using what they know often leads to censure or even punishment.
So the "good kids" who follow all the rules will leave that stuff at home and play dumb in school. The "rebels" who like to push boundaries will make sure the teachers don't find out.
So I'm betting there are plenty of bright kids who know a lot about computers in the author's classes, and they're all keeping their heads down. Doubly so if the author has a reputation for being angry and judgmental. (I didn't think this article was particularly offensive, but other commenters disagree.)
So the "good kids" who follow all the rules will leave that stuff at home and play dumb in school. The "rebels" who like to push boundaries will make sure the teachers don't find out.
So I'm betting there are plenty of bright kids who know a lot about computers in the author's classes, and they're all keeping their heads down. Doubly so if the author has a reputation for being angry and judgmental. (I didn't think this article was particularly offensive, but other commenters disagree.)