The key point I see on the National Guard issue is that they are a fighting force, not a disaster recovery force. That is what we are spending hundreds of billions of dollars for [the Guard] over the years. It is like owning a car. In my family, for example, we have one car. I work at home (I'm a writer) and my wife uses the car to drive to work. Now, if our son breaks his arm skateboarding while my wife is at work, I won't have the car available to rush him over to the emergency room. So, is it bad that my wife uses the car for its primary purpose? No. We wouldn't spend $10,000 a year just to have the car sitting in the driveway ready for those rare emergencies, but having a car that is used primarily for driving to work means that it is also available for emergencies the rest of the time as an added bonus. So it is with the National Guard. If we weren't using them sometimes as a military force, we wouldn't be spending all that money to hire, train and equip them, so they wouldn't be available on those rare occasions when a disaster occurs anyway. Even if it would help to have those extra National Guardsmen available at this moment in New Orleans, if they weren't occasionally used for warfare, there would be no Guard at all for use in disaster recovery. As it is the state has thousands ready to deploy.
I'd also like to point out, as another Powerline reader does at the link, that a lot of the people making this same point were the same people implying that the National Guard was somehow a lesser form of service when they were trying to score points with the President's military service.