I’m the ombudsman at PBS and I don’t want to be glib or dash off something on Twitter that I would quickly regret, or that could easily be misunderstood, or could be used to either discredit me and my work or PBS. I had the same policy about pre-social media venues when I was the ombudsman at The Washington Post. So that brings me to the real self-inflicted wound, which was a tweet by PBS NewsHour co-anchor Gwen Ifill on Wednesday—after it became known that President Obama had secured the necessary number of Democratic backers in the Senate to ensure...