I guess he wasn't sure what direction Duncan wanted it to go. Either way, Toby has said that he wanted to be cast as Thrall in a sequel and he said that he is excited to see Orgrim become the wise teacher for Thrall. Duncan has also said that in the first movie, Durotan was the wise one and Orgrim was his sidekick. But now, in a future film, Orgrim has to stay strong and be the wise one. He was already pretty wise at the end with Gul'dan. He didn't want revenge for Durotan's death. But he wanted to fufill Durotan's wish; that Gul'dan is crazy and that they shouldn't follow him.