Tom points out to Woltz that he hasn't threatened him and thinks to himself that the Don taught him that way.
Tom doesn't threaten Woltz openly, but in fact he does: He's talking about labor trouble and a film star using heroin. Woltz hits the nail on the point: “I understood perfectly,” he said. “That’s the Mafia style, isn’t is?"
Their style is to let their opponent not lose their face.
