That article is telling you only that the driver resides in ROM. That does not mean that you cannot format or otherwise install the drive. It just means that you need a special formatting tool (Internal HD Format) to prepare the drive correctly. As the article says, use of other formatting tools will inevitably result in a driver being installed on the drive, preventing Internal HD Format from doing its thing, and thus preventing the PB150 from using the drive.

Installation of a driver is not the same as initialization or formatting. These are separate operations.