AFAIK, all forms of "integrated" headsets, both the true integrated design where the bearing seats are machined into the head tube and the "zero stack" type where shallow cups are pressed into flared ends of the headtube, use cartridge bearings. Therefore, the actual bearing balls roll against races that are part of the cartridge and should never really touch anything in the headtube.

So, if your friend had his headset "destroyed" I can only presume that one of the cartridges came apart through misadjustment, neglect or a manufacturing defect. He needs new bearing cartridges and the frame must be inspected to assure the bearing seats weren't damaged by the broken pieces.