Jeff Swensen/Getty Images When I was a columnist for the Jewish publication The Forward a few years ago, I was an outspoken critic of the Women’s March leaders , who despite their progressive politics, had questionable associations with antisemites . I felt that Tamika Mallory, in particular, had used antisemitic rhetoric herself. At the time, I was surprised and gratified at how quickly the story was picked up by other news outlets and how easily attention was brought to my sincere concerns. In a matter of days, I was appearing on cable news, and a social media debate raged for...