In the lead-up to the 2016 election, Democrats fretted openly about the possibility that Donald Trump, being a rather poor sport, might refuse to acknowledge an election loss. To be fair, Trump refused to state that he would accept election results, depending on the circumstances: “I’ll keep you in suspense,” he stated in his Oct. 19, 2016, debate with Hillary Clinton. Clinton, for her part, called his statement “horrifying,” adding that he was harming American democracy. Trump, of course, won. And Clinton spent the next couple of years suggesting openly that she had been robbed in the election. Democrats blamed...