"In Australia and China, online Apple Store shipping times for the iPhone 5s rapidly slipped to 7–10 days for all colors and capacities, with immediate unavailability of the 64GB gold version."

Speed of unavailable being reached seems like the best metric available right now, and that suggests more demand in Asia than other places (although it's early and hard to draw conclusions - so I guess I would agree with your point that Business Insider jumped to conclusions a bit, really just seems like Apple wildly underestimated demand for the whole 5S series).