We all know Norton is a gifted actor-writer-director who likes to engage on his projects, even in the editing room. He's not alone. Many actors prefer to be in control of their movies. But actors-for-hire are being paid to deliver for the filmmaker. Or, if it's a Marvel franchise, Marvel.
Here's my advice to Norton: learn from James Franco.
Norton was great as Bruce Banner/The Hulk and might be playing the role again if he followed the same logic when he acts for hire. By the way, Norton's contributions to The Hulk were considerable. But clearly, Marvel weighed the pros and cons of bringing him onto The Avengers and decided it was easier to proceed without him. Did they need to bad-mouth him in the process? No.