No one at the tiny roadside Blue Ridge Diner knew for sure whether Mark Robinson would show up to his campaign meet and greet on Monday, nor did they know whom to ask—the GOP gubernatorial nominee’s staff had just quit en masse. Robinson’s campaign said the day before that its manager, deputy manager and a half-dozen other staffers resigned, following a report describing his allegedly antigay and racist comments a decade ago on an online pornography forum. That was the latest in a string of...