The author seems to only look at a narrow case that supports his argument. Imagine you start out with 2 shapes and 4 directions, but you eventually get additional requirements for 20 more shapes and 4 more directions. Now you have much more code, introducing room for errors, making it harder to change, and making it harder for new employees to understand.
I agree that he should have told his coworker ahead of time, but I also think his coworker should be open to understanding why his code may cause problems and be ok with it being changed.