The point I was making is that it's pretty meaningless for a company to get shirty about that 250-300kg fuel. I know there are accountant types who will work out precisely how much it will cost in extra fuel burn having this additional fuel on. However, it equates to about 10-20 kg per hour flying. The point is that the normal variation of fuel burn will be of the order of 200-300 kg per sector. So it is virtually impossible to detect this "saving" in the normal variation. On the other hand, it is very easy to work out the direct costs of a diversion because you can't land with less than final reserve fuel. It isn't so easy to work out the secondary costs - those people who won't fly with your airline again, the knock on cost of the delays etc.
One thing that interests me is that, if you take sector fuel, and get away a few minutes early with no delay at the hold, you might not be able to hold until your scheduled arrival time before diverting.
"Ladies and gentlemen, we are diverting to another airport."
"But we're not even supposed to arrive for 20 minutes!"