Should US (or any other airline for that matter) be charging a baggage fee when pax are protected on their flight? I say this because typically, when an airline puts you onto another carrier, they have to pay that carrier the full fare. Accordingly, pax typically (or maybe even always) get booked into Y class. AFAIK, all airlines waive baggage fees when someone is traveling on a Y fare, which is the case here. So, why would US collect baggage fees in this case?
Just a thought.