Boy, is this a fallacy. All it means is that Northwestern swaps with another bubble team. The team the Wildcats jump to make the NCAA is in the NIT. Iowa has to win. Whether Northwestern wins or loses is irrelevant to Iowa's chances for the NIT. I don't know why people think that if Northwestern makes the NCAA it opens up another spot in the NIT. It doesn't. Northwestern just switches spots with Cincinnati, for example.
what it does due is make Minnesota less likely to go to the NIT, which potentially does open a spot for Iowa.