Four years ago, Nick Fuentes was unwelcome pretty much everywhere. The young far-right influencer was barred from nearly every social media platform and an array of payment processors, either for violating hate speech policies or for encouraging rioters to storm the U.S. Capitol on Jan. 6, 2021. A 2022 documentary by a sympathetic filmmaker called him “the most canceled man in America.” Now a person who once called Adolf Hitler “awesome” has more than 1 million followers on Elon Musk’s X. He recently recorded a cordial interview with Tucker Carlson that more than 5 million people have watched. And he...