He might be, but its worth noting he isn't originally from Montana. Neither is Assaultforte, but that seems like the type of edge Democrats would need.
And neither is John Heenan, lol. But honestly, these kinds of attacks are incredibly silly anyway. As for Kier... I think he would probably be a slightly stronger candidate than Heenan (the latter would definitely fire up the base and might come across as very authentic, which matters a lot, but I think he'd struggle to get the last 2%-4% he needs to win). In any case, I'd say this race is Lean R, but I'm skeptical that there will be
that many Tester/Gianforte voters. Gianforte has a very low ceiling but also a relatively high floor. Democrats shouldn't underestimate him again, but he's obviously not some unbeatable titan either. Gun to my head, he wins by about 5-6 points in the end.