The point is they found that members of the press or bloggers who want these assets in the first place are not bothering to drill down to the Press section; they're just grabbing it right from the root index, causing sub-optimal assets to propagate through the media, which reflects poorly on the brand. This way, Github makes sure they're getting publication-friendly versions of their logo when people do that. Ultimately, ensuring their brand is well-represented in the media was deemed more important than avoiding inconvenience to a few power users.