I concur, and I'm the author. It's a wonderful introduction to Big O for folks that struggle with it. My post is merely a tool to help refresh my knowledge of fundamental concepts. William Shields does an excellent job of making Big O approachable to non-CS majors.

The only passage I take issue with is his description of O(n) arithmetic examples. In my thinking addition/multiplication are O(1) but I blame that view on years of thinking about FLOPs and letting thoughts of # of operations conflate with big O notation. In practicethe example of adding two large integers is a single operation, or at least a fixed size handful operations for arbitrary precision.