It seems sort of harmless. I realize hes got a gun... but he's too casual. Unless he's just that carefree and reckless that he'll just snap and attack
As a matter of fact, that's precisely what comes next.
The quote "you're a daisy if ya' do" is what he says, after being threatened, and making this 'open' gesure. He's deliberately presenting an enormous target for his quarry, who does, inevitably lose, despite the gesture, because of Doc's agility and fast reflexes.