It was the first test of an emergency broadcast that the President would feel everyone would need to know immediately. On the local news they said it would be for things like notification of a nuclear attack or something, because otherwise the notices would be more localized for things like floods, as someone mentioned above.

While I'm replying to a message of yours for the first time, I must say that I often get a chuckle from your location. Every time I read that quote, I don't know if it's from somewhere else, but I hear it from the Robot Chicken Star Wars rap from years ago and the next thing I say in my head is, "I'll blow your planet up!" That would also be a reason for the presidential emergency text message.