Kevin Rusch was at home on a recent Sunday evening scrolling through Facebook when he saw a photo that shocked him: A man with an American flag bandanna wrapped around his head stood at a rally demanding Wisconsin lift orders that had shuttered schools and businesses. That man was David Murdock, a cardiologist from his hometown, Wausau. And, like the hundreds of other people at the rally, Murdock was maskless and did not appear to be practicing social distancing. In one photo, Murdock’s arm was slung around a priest, with the two holding a sign that read “We are an...