Ugh. Has little to do with Montana liking Trump.
Look, most Montanans weren't crazy about Trump, they just hated Hillary. But using your logic, Gianforte should have beaten the Democrat Governor he ran against, right?
People here didn't even like Gianforte that much. He won because he was running against a guy who had been a career long mediocre musician whose recent accomplishments include not paying his taxes, stiffing his contractor, and falsely reporting his income. But yeah, Gianforte won because of Trump.
Fwiw, Gianforte has given millions to schools/universities, apologized to the state, his supporters, the reporter he hit and the reporters who saw it, for his physical outburst. And tbh, if I was him, I might've done the same thing. When a reporter trespasses, repeatedly asks the same questions ignoring your responses that you'll get to him if he waits, while he shoves his phone in your face...yeah, I'd deck the guy. It was completely the wrong decision, but I freaking get it.
Trump won the Montana primary by a landslide, maybe more than any other state.