As it is represented "photojournalism" and is held out as such, then yes he went too far and the AP were justified IMO.

Just like journalism shouldn't be about altering or manipulating the facts to embellish a story, likewise altering an image in this way is taboo. But I acknowledge I am perhaps just naive and idealistic.

If it isn't being represented as photojournalism or a factual recording of the actual scene, then manipulate the bejeezers out of it and in it in any way you like.