It does, but the author's point, I think, is that dividing by GDP isn't particularly meaningful. They argue that the cost of additional borrowing is a better me

It does, but the author's point, I think, is that dividing by GDP isn't particularly meaningful. They argue that the cost of additional borrowing is a better measure - will people loan you more or are they getting nervous they won't get their money back? You could divide by other numbers - an example the author gives is hard assets- and come up with a different percentage.