The chair of the Federal Trade Commission, Lina Khan, is using the crisis facing aerospace giant Boeing to press her case that “national champions”—firms deemed too important to face antitrust enforcement—invariably behave badly because they are protected from competition. Whatever their source, Boeing’s massive problems are not due to a lack of competition, as Khan tried to argue in a recent, head-scratching speech that ignored the U.S. plane maker’s decades-long rivalry with Europe’s Ai...