There is a simple economic reason for kt's point of view.
In an airline operation, engine maintenance cost is a very significant part of the corporation's total cost structure, and so flex thrust makes much sense. Costs make the difference between profitability and bankruptcy.
In kt's world, the engine maintenance cost (in fact the whole bizjet operation) is a very small part of the corporation's total cost. If engine maintenance cost were zero, or if it were tripled, wouldn't make a pfennig difference in the corporation's EPS.
