It would be interesting to break down the cost of an event like this.
I don't know the answer to your question but imagine the cost of putting the pax in hotels, transporting them to and from the hotels, and dealing with the pax in Dallas that were due to jump on that airframe in 18hours time , would be even greater than the wasted gas.
Anyone have any experience with the costs involved when this sort of thing happens? Do the Airlines even bother analysing each event and costing it?