Moving target
The trick of GS MINI is that it will decrease the need for thrust lever movements: with a positive gust, your speed instantly increases. With a stationary speed target, you would have to pull back power to stay on speed. With the increased target speed, there is no need to change power, you are still/again on target speed.
With a sudden negative gust, your actual speed, but also your target speed, will drop, so again, just maintain steady power.
In fact, with the thrust levers you are doing the same as on a Boeing, where you set a fixed speed target with sufficient margin above Vref and let the speed just bounce around with the gusts (keeping steady thrust), as long as speed deviations are not extreme of magnitude and/or duration.