Hong Kong businessman Sam Tsang does not like to talk politics. As a senior business consultant who travels frequently to mainland China and Taiwan, he knows silence is often golden.He was in for a shock when, one night in mid-July, his boss introduced him to two “mainland researchers” who were visiting Hong Kong. That evening, all they talked about was politics.It was just two weeks after the storming of Hong Kong’s Legislative Council chamber by young protesters, angry at the government’s…