It's mainly what he didn't say. He had a stone cold look of anger on his face and gave the interviewer extremely short answers such as (paraphrasing):
"You just won the gold medal. What a great effort. How do you feel? What was going through your mind?"
"I feel fine." (emotionless stare)
... and on from there in similar fashion.
He should just put a post it on his forehead that says, "I hate America, I hate whitey."