The possibility of "pinning" NAU within the 20 is probably the same as getting the first down on that 4th. Therefore you have to assume you just told NAU "here's the ball 30 yards back from where we just had it."
Assume the D forced a 3 and out and punts, 40-45 yards down the field. And the offense needs to go even further to score a touchdown in a game which everyone admits knows the offense had trouble moving the ball....or in layman's terms hoping to get back to where they were...and likely facing a 4th and short again just with less time on the clock. The statisticians will have told you going for the original fourth down would have lead to a greater chance of winning the football game.
Edit: Not to mention they were down 8 points at that point ( "1.5 scores"). Which increases the desire to need to go for it on fourth down at this point in the game (7 minutes left).