As a student witnessing the amount of cheating going on, I was always surprised about the noise raised by teachers on it: I always felt that my score was my own, and didn't care about comparing against others.
Perhaps that's why I didn't care?
Another thing is that college is voluntary, and everyone takes the courses for some perceived gain. If it's just a diploma with high GPA, I let them be.
There are also plenty of ways to legitimately score a high grade without really engaging with a course (basically silly ways to study just to pass), which in the end result is not much different from simply cheating (there was no appropriate engaging in the material) — while the main difference is in fairness, that's a moral value that's beyond some random teacher's ability to teach adult students — so I don't see why bother.
The main question I have for the author is if they would have offered the same get-out-of-trouble alternative syllabus if they had 10% of the students cheating? Basically, how influential was the proportion of students to be failed in their huge investment in reworking the course?
Obviously, they did a bad job with the original syllabus in promoting exactly the behaviour they didn't condone, but one should never discount the thrill humans experience in engaging in risky behaviour (like figuring ways out to cheat which is sometimes more work than studying, but more thrilling — and helping others along the way adds a nice cherry on top).