She knows the looting that will occur if she evacs.
Oh, I didn't even think of that!
The news conference delay is probably because they were waiting for the latest info from the NHC, which goes public around 12:30-45 central, and are probably now digesting the updates before making the final call.
Also perhaps by calling it for noon and then having it stretched out it will get more viewers(potential evacuees) as more become aware of the news conference.