Agreed. Something can happen and probably will. However, the way he put it, the Earth was on its way out, in a dramatic fashion that is sure to take the moon with it. Seems like a scenerio better suited for a double episode of Transformers.
Basing something substantial on the moon is a good idea. As noted earlier, it decreases the size requirements for launch vehicles substantially. Just look at what it took to get the Apollo teams back verses what it took to get them there.