The author admits that "logical punctuation" is an equally valid form, and can even point to publications for which it is the house style. So why is he taking p

The author admits that "logical punctuation" is an equally valid form, and can even point to publications for which it is the house style. So why is he taking points away from his students when they use it? It strikes me as a rather petty way of enforcing a particular stylistic choice where it doesn't really matter.