On Aug. 12, the day a judge unsealed the search warrant that the FBI had used to take documents from Donald Trump’s Mar-a-Lago estate, friends of mine, as well as Democratic lawmakers and commentators, began to say that the news couldn’t sway Trump’s supporters. The revelation that the former president squirreled classified documents out of the White House and might have violated the Espionage Act ought to be a red line, they said. But it wouldn’t change any minds.