GOP candidate threatens to shoot up fellow Republicans in new campaign ad (video)

Threatening to kill Democrats with weapons has become a main staple in GOP candidate ads, but here's a twist: Republican Missouri Senate candidate Eric Greitens threatens to shoot up his own party as he goes "RINO hunting" in his new campaign ad (see video below).

"Today, we're going RINO hunting" the former Missouri governor, who resigned after allegations of sexual assault, says as he cocks a long shotgun. The ad then shows armed men in camouflage storming and firing into a house, presumably one that belongs to a "Republican in name only."

"Join the MAGA crew. Get a RINO hunting permit. There's no bagging limit, no tagging limit, and it doesn't expire until we save our country," says Greitens, whose own ex-wife accused him of "physical violence toward our children." 

This ad follows Greitens' threatening ad in April in which he and Junior Trump enjoyed target practice together while saying, "Liberals beware."

How is this legal?