Because it isn't nearly as big of a factor as you are making it out to be. We are going to get every team's best shot from here on out, every single game, because of who we are and what we're ranked. Do you think that UNC would magically relax somehow and not play as hard on Saturday if they'd won tonight? Sure, they might be desperate for a win on Saturday, but that doesn't mean that they are going to play BETTER.
Meanwhile, there are a lot of "psychological" factors working in our favor, that more than offset the mojo some of you are pointing to as favoring UNC. We are playing at home. Despite their inconsistent record, this is still UNC and our players are likely to be sky high to play them. We are battle tested and have played in a lot of close games that we've managed to pull out at the end--so we won't get rattled if they hang around for awhile. We execute well at the end of games, whereas UNC does not.
So again, the simplistic statement I'm fine with, but you are misapplying what it means. The same way that you are overestimating how much UNC winning or losing will impact Saturday's game.