Estime was guaranteed to score, and there was only 30 seconds left on the clock.
Yes, I know a 18 yard field goal attempt (from the 1 yard line) is almost all but guaranteed, but in this case, almost isn't good enough. Duke's front seven was getting excellent penetration all night, and they could certainly have had a chance to block the field goal. We could have also mis-snapped, or Shrader could have shanked it.
You take the sure score, to go up by more than a field goal's score, forcing your opponents to drive 75 yards to paydirt. The defense was playing well all night, and with not having to worry about the quarterback runs (they had to pass on that last drive), a lot of Riley Leonard's effectiveness was taken away.
Someone like Sam Hartman can drive a team down the field in 30 seconds because he's primarily an accurate and precise thrower in those last second drills.
Riley Leonard has his best passing success only when he's also a threat to run, since that allows him plenty of single coverage options. He didn't have that single coverage benefit during that last drive, for the two plays that it took, and that sack was as much of a coverage sack as it was Cross and Liufau getting to him in time.
Now, maybe if Duke had someone like Rocket Ismail on their return team, maybe that's a different story, but there's only one Rocket Ismail, and nobody else is his equivalent.