"If the reporter had explained that he was intentionally trying to simulate "normal use" by not plugging in the car at night."

That runs at odds with a claim made on Tesla's site: "The Model S battery will not lose a significant amount of charge when parked for long periods of time. For example, Model S owners can park at the airport without plugging in." (http://www.teslamotors.com/models/facts)

Either Tesla is lying when it claims that it won't lose a significant amount of charge, or Tesla is not lying (which would imply that not charging overnight doesn't really matter)