The question is, why did he do it? Usually people only lose their temper if in a bad mood. Surely he must have thought, tomorrow I'll win, I just have to make it one more day to have my vindication. Or does he know some internal polling we don't know?
There was a rumored R internal with Greg at +2, Bernie was drawing big crowds & Quist was hammering Gianforte about Trumpcare in the last 2 weeks with many ads & grassroot stories! This reporter was asking him about Trumpcare (damning CBO report came out) & his support for Trumpcare & he lost his mand & body-slammed & assaulted the dude !
Gianforte was feeling the heat & this race was becoming a toss-up!
Edit - Apparently this reporter wrote the piece of Gianforte's investment in Russian companies which has been sanctioned or something so may have been a grudge who knows !