I'm from the Midwest. I'm guilty of saying it. But that being said, 1) there was a time where I was seriously contemplating declaring bankruptcy, so I think that qualifies under the authors definition of 'poor', and 2) I don't see the value in making this distinction of 'poor' and 'broke' anyway. Sure there's a matter of degree of difference involved, but it just sounds like making an argument of semantics.
If the general usage is using your word wrong, invent a new word for it and popularize it, or just be more specific. Meaning of words gets co-opted and morphed by the public all the time anyway. I don't see this author creating any serious movement towards reclaiming the word "poor" for what they think it really means.