As a professional graphic artist who has been working with Photoshop since 1995 I have to agree with Alan.

The unsavvy individual who tries to make a 6x4 print from the 800 x 532 image(saved in photoshop at 125ppi, or any other ppi setting) will get a less than stellar image, which is Ned's ultimate goal. The savvy individual who prints at 3x2 will get a sharper, but smaller print. And someone who grabs Ned's photo and applies proper post-processing can probably improve the image somewhat, but certainly not to the extent that they could have if provided the original image, with larger pixel dimensions.

Simply put, spreading 800 pixel(dots) over 6 inches provides less detail than spreading those 800 pixels over 3 inches.