A few days before the BBC took Gary Lineker off Match of the Day because he had tweeted his criticisms of the Tory government’s asylum policies, I happened to be at a festival on the far side of the world. I was speaking at Writers’ Week in the Australian city of Adelaide, where outrage over a tweet also led to demands to cancel one of the participants, or indeed the whole event. Yet this was not quite the same grim story. What happened in Adelaide was in fact a good example of what sanity looks like in these situations. It...