Keith Harmon (inset) knows politics and business don’t mix, especially in the midst of a passionate presidential election. But the co-owner of Tres Gatos, Centre Street Cafe, and Casa Verde says he wouldn’t think of prohibiting his employees from speaking their minds privately. So when one of his employees at Centre Street Cafe in Jamaica Plain made his opposition to Republican presidential candidate Donald Trump known on Facebook — he posted a video clip calling a Trump rally racist — he didn’t tell him to take it down. “We have a pretty strict policy about not getting involved in politics,’’ Harmon said Wednesday. “But this was his personal point of view posted on his own Facebook page.’’ Still, there were consequences for the restaurant. Harmon says the post was shared among Trump supporters who then posted a series of negative reviews and comments on Centre Street Cafe’s Facebook page. “We started seeing one-star reviews and people calling [the employee] crass things, stuff I would consider homophobic innuendo,’’ he says. Harmon says he has received notes of supports from friends and colleagues in the local restaurant industry. “I will say this points out to me what a divisive election this is — and what an important election it is,’’ he said. “The fact that support for someone to the highest office manifests itself in this sort of behavior is incredible.’’