Operation Niwi didn't work as well as expected due to a phenomenon in which if you place infantry in a situation where their only choice is to fight or die, they will fight extremely hard. Sun Tzu writes about this, and both the Germans and Soviets learned about it on the Eastern front. So in actuality, while Niwi was a unique aerial stunt, it delayed the western campaign.
TLDR: The Belgians put up a ferocious fight after being surrounded by the Germans from Operation Niwi. Delayed the entire campaign.