Question: Why wasn't Chris Cooper credited for his role as Norman Osborn?
Question: Who is in charge of Oscorp now?
Answer: Donald Menken, the Vice President of Oscorp, framed Harry for covering up Max Dillon's accident and has him removed so he could take over the company. By the end of the movie, Oscorp would now be under his control.
But he was killed in a deleted scene.
Deleted scenes don't make for canon content - it has to involve a degree of guesswork. Some deleted scenes happen, we just didn't see them in the movie, others are movie ideas that were cut out precisely because they don't fit the movie as released, so didn't happen. No way to know which is which, and this is just a thought exercise anyway.
So this is possible that, at the end of this movie, Menken is still alive, right?
Answer: Cooper's role was a cameo. And often, when well-known or well-respected actors appear in surprise cameo roles like this, they go uncredited. Usually to either try to maintain the element of surprise, or try not to overshadow the rest of the cast.
TedStixon