When Congress passed the law that required TikTok’s parent company, ByteDance, to sell it or see it banned in the U.S., it was partially motivated by the fear that the Chinese government might use TikTok to contort Americans’ discourse, pitting people against one another and eroding their trust in the democratic systems that define American politics. On Friday, at the oral argument that will determine TikTok’s fate, Chief Justice John Roberts made a joke underlining this risk: “Did I...