I don't think I would change anything he reacted normally. Is understandable that he got nervous. I loved his performance and he sang great. He could not have done a better job.
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Change is not merely necessary to life. It is life.
He... needed to repeat the semifinal in the final. I guess he was getting tired or something at the final, because he got sharp all over and didn't attempt the high note at the end. But the semifinal was OMGEFFINGAWESOME!!!!!!