These Rules apply to Nat Geo's Photographic Competition, they do not Apply to Nat Geo Photographers that are supplying Articles/Photographs that will eventually go into the Magazine, Yes, there are rules that apply to these Guys as well, but "No Manipulation at All" is not one of them.
Have you ever seen a B&W Image in a Nat Geo Magazine ?? Manipulated.
Have you ever seen a Stitched Panorama in a Nat Geo Magazine ?? Manipulated
Have you ever seen an Image that employs stacked focussing in a Nat geo Magazine ?? Manipulated
Have you ever seen an Image that's been cropped etc Saturation levels increased etc
You get the Picture I'm sure.
Why on earth are fish eye lenses not acceptable when telephoto lenses are??? Sounds biased to me!
But hiring fixers, traps, harden case, advanced electronics, $10,000 (or higher) budgets are allowed, .. seems that anything goes in the field (as long as us mere mortals don't have access to it) but accessible to the common folks, then it is off limits.