Here is the "there must be an explanation" explanation. As I tried to explain in this recent article in the Atlantic, the people in charge of China's propaganda apparatus are among the least worldly and most rigid-minded people in the entire country, with absolutely the least feel for how people in other countries might react or think. So apparently some of these ignoramuses considered it a good and prudent idea to cut off Obama -- even if the vast majority of their fellow citizens would consider such paranoia to be extreme and bizarre. Also, within a part of the government where orthodoxy is everything, an official takes no risks by being too hard-line, but could get in trouble by being too permissive. Still; it is an incident whose importance may grow as time goes on. They couldn't even stand to hear Barack Obama speak!
China's "Nobama" Policy
The Great Republic decided to black out President Obama's Inaugural Address.