Official thoughts from developers?

Actually, if they can detect it in one zone, they can probably detect it in all the other zones, too, it's just that they are focusing their efforts there in order to reduce processing times, as Ghost Iron has so many uses these days.

Think of it - instead of hunting bots in zones gatherers have largely abandoned, you focus your efforts in the zone where the bots are. They are simply prioritizing the data from Pandaria over the data from all other zones. This doesn't mean you won't get banned for Cata gathering, because it's undetectable, it merely means your activities will be lower in the processing queue, but eventually they will get to process your data and you will be discovered, especially with Public profiles. I wouldn't count on the Randomize Hotspots setting either, because Honorbuddy randomizes the hotspots the same way for all players, so if another buddy is using the same hotspots, chances are their Randomized route will be the same as yours.