>> How in the world do you take someone with no prior exposure to one of the fundamental skills of the field and, in four years, turn them into someone to whom it would be appropriate to give a college degree in computer science?
You don't, unless they have the passion, drive and natural aptitude. The author makes very apt comparison to music and expresses that there's really no way out of the conundrum in that field, but wants to find one for CS. Just like music, if you want a university-level program where anyone can come in and succeed in a limited amount of time, you have to rely on high school curriculum to provide the foundations.
The problem is perception. Given a standard high-school curriculum, it's obvious that a student won't succeed in a university-level music program without becoming specialized in high school, but it seems like students should have the foundational knowledge to succeed in a university-level computer science program. Unfortunately, it's just simply not true.
The author says this in the comments:
I don’t want to effectively require students to choose early in high school whether or not they want to study Computer Science in college. While computing skills are clearly beneficial for everybody, I hesitate to make the claim that computing courses are more worthy of limited curriculum time than other disciplines such as foreign language.
Unlike the author, I don't hesitate to make that claim at all. People often lament that students graduate high school knowing basic history, algebra, physics, biology and the like, but don't understand how a credit card works, what happens when they push the gas pedal in their car, or most importantly, simply how to think logically and critically. Shifting part of the mathematics curriculum to focus on logical thinking, regardless of whether it's presented using programming or not, would go a long way towards enabling success in fields like computer science, and would make graduating high school students more well-rounded to boot.