Right-wing pundit Tucker Carlson used the latest episode of his online talk show to interview a self-proclaimed “historian” who promoted falsehoods about the Holocaust. The episode of Carlson’s eponymous show on the social network X/Twitter earned plaudits from the site’s billionaire owner, Elon Musk, who wrote in a since-deleted post that it was “Very interesting. Worth watching.”  In the interview, Darryl Cooper, author of a Substack with around 112,000 subscribers, told...