> I haven't read the book and dunno about PG's definition of spaghetti code, but "we can make all these types of modifications without even looking at the rest of the code" sounds like the opposite of what all people I know call sc.

That was exactly my thought as well, I had to reread the part twice to make sure. This is the definition of maintainable (or maybe even well-designed) code when all its parts are carefully isolated.