"The reason was for the national interest," said Chen Qigang, the ceremony's musical director, in a state radio interview. "The child on camera should be flawless in image, internal feeling and expression. ... Lin Miaoke is excellent in those aspects."
Apparently the initial rehearsals were reviewed by the old men of the politburo, who deemed the actual singer, 7 year old Yang Peiyi, "Not hot enough to be the Chinese Britney."
Incidentally, the new Olympic Stadium is said to be able to host the simultaneous executions of over five hundred political prisoners, a 75% increase over the previous venue.
(H/T to the Munchkin Wrangler.)