It's possible that they're not even at war. Maybe Marvel said, "Okay, here's what we want to do." And Norton said, "Um, actually, I know I said I would do it, but some stuff came up and now I'd rather not." And then Marvel said, "Oh. Well, that's too bad, but we totally understand, Ed." And then they all sat down and shared a pot of tea and some biscuits, and everyone was friends.
Not everything has to be a huge deal.
Or, alternatively, maybe Norton took a sledgehammer to the producer's puppy, and they put a bounty on his head as he fled to Bogota. Who the hell can say at this point.
