The Day the Earth Stood Still (2008)

Factual error: The electrical power grid fails, depicted by a series of shots of city blackouts and equipment shutdowns. When the power goes out, the lights of an oil refinery go out as well as the flare. In actuality the exact opposite happens to a flare when powered equipment such as compressors and cooling devices fail simultaneously. The flare is not an electrically powered device and is designed to stay lit during power outages. All excess pressure is immediately vented to the flare stack within a second, causing an enormous flame and smoke cloud that will be visible for several miles.

Klaatu: If the Earth dies, you die. If the human race dies, the Earth survives.

Trivia: When Klaatu is shown on the tv as an escaped convict, the phone number shown to call to report him is not the usual 1-800-555 number, rather it is 1-800-472-0391 which is the Alaska Weather Information Hotline.

Question: If Klaatu chooses to save the policeman that he injures/kills, and seemingly has the power to do this as many times as he wishes, why does he let the man using the Polygraph die?