dont worry about it. my guess is the 5 megapixel rule is so that would be fair to camera phone or to be exact, iphone users.
if your camera can go below 5 megapixel, fine but if cannot then boh pian but have to use image editor to resize the photo. Thus far, they never said cannot use image editor to resize the photo and since this isnt the first time this is held, i am pretty sure they know what to look for in "edited" pics.
Only thing is what will be their ruling on obviously studio-taken photos and the use of non-natural props?
and hopefully this year, its not the so called dryfit shirt of past years.