There are a number of ways for Duluth to not be coming to Madison.
If you load up the 'defaults' - "autofill higher seeds" - on Grant's predictor, Duluth is #10 and Wisconsin is #1 ---> Duluth goes to Ohio State,
And if Duluth is #10 and somebody outside the top 10 wins their conference - the easiest or most likely is Mercyhurst beating Penn State to win AH - then Duluth doesn't make the NCAAs at all.
Of course, if Duluth is #10 and Wisconsin drops to #2, then #10 Duluth IS coming to Madison. And, go the other way, Wisconsin #2 and Duluth #9, then they don't come to Madison.
Lots of possibilities besides Mankato sweeping Duluth.