"Naked" is a real stretch. It's basically a black and white, lumpy x-ray viewed from a remote control room.
That's the reason why there are more recent devices that hide the nudity and only show abstract figures with suspicious body areas highlighted.
But the airport visitors has no way of knowing what generation the software is, i.e. whether they are visible in the nude or not. Also, the unmodified images by still be stored on the device - who knows?
Some posters are claiming the screens don't show the raw images anymore, but what happens to those scans? Betting they don't discard them. Ever.