Really I mean literally. If they showed Peter's plea to him for help, and we then see Harry's arrival at the battle royale, it would've just been better. Plus with Harry and Peter's exchange before he died it would help imply he made a decision own to let his revenge go and help his friend when he needed it most.
Better yet, in addition to that: instead of Peter yelling at Harry that Norman killed himself, in their first fight when Harry was obviously beyond reason; Peter could have told him the detailed truth when he went to Harry's place. That Spider-Man and Norman were in battle, Norman went crazy, and when Norman went in for the kill he accidently killed himself. Throw in the classic Parker guilt, with how he promised Norman not to tell.
(Of course one suggestion can be fixed by the editor in seconds and the other would require a reshoot, ha.)