Trump’s not winning Montana by 14 in this environment (I’d expect this kind of margin in a very close election, but not when Democrats are consistently leading by high single digits nationally), and Gianforte isn’t winning by 10 either.
Montana was 22 points to the right of the nation in 2016. If Biden is leading by 8, Trump winning MT by 14 would be a net zero trend. Do you think MT will trend to the left by that much?
Remember that Bush 43 won MT by over 20% in each of his elections, yet that didn't prevent it from swinging more than 10% to the left in 2008.