A lawsuit accusing United Airlines of breach of contract over a frequent-flier mile fee can proceed, a federal judge held.U.S. District Judge Robert M. Dow Jr. of the Northern District of Illinois ruled that while the complaint may fail on its merits or as a class-action lawsuit, the plaintiff’s allegations do not lack plausibility.Stephen Simoni filed a putative class-action lawsuit against United Airlines Holdings, Inc. (UAH) and United Airlines, Inc. in Cook County Circuit Court in 2021, alleging breach of contract. Dow …