The airbus ground speed mini does not work that way, all that it means is that if there is a strong headwind that it will slow down LATER not earlier, it will gradulally reduce to Vapp at touchdown.
It is bascially to protect you from windshear by maintaining a higher IAS and so buffer from the stall, incase there is a sudden lull in the wind.
There is nothing to stop apilot from overriding the ground speed mini (managed speed) by manually selecting a speed.