It was used as a demonstration photo in a famous photo-editing program which was used to fool the world, but the image is ostensibly a real photo, not a fake image.
Or take this description of the edited image of Elvis:
> the United Press agency decided to create a mock-up of what the king of rock’n’roll might look like with the typical GI hairstyle, retouching a photo of the singer to remove his quiff (and leaving him with a somewhat disfigured head). “Not all manipulated photographs are intended to deceive,” notes Mia Fineman, a curator at New York’s Metropolitan Museum of Art
Only the headline says "images that fooled the world"; the article is about something different.
I'm a scholar in this area, and that article is shit.
Photoshop is such a popular tool for image manipulation that it is a verb "to digitally alter (a photograph or other graphic) using image-editing software such as Photoshop".
Inclusion of one of the first ever photoshopped images in a list of famous fake images, even if just a tech demo, seems entirely reasonable.