[The Saucepan Man]

Yes, you're right. Sam does apologise. In which case, the tragedy is not in the fact that Gollum's possible redemption is lost by Sam's reaction. Gollum could have accepted Sam's apology and the fact that he does not reflects more on him than it does on Sam. Rather, the tragedy is in the fact that we see that Smeagol/Gollum might have been capable of redemption. And, in the films, we see that in the debate scene in TTT. As I said at the outset, Jackson moved the moment forward.