That’s why he had to pay for the bag. If the carry on doesn’t fit under the seat- it has to be paid for, so it appears he isn’t owed a refund of the bag fees and he will be charged again when he returns. Whoever purchased his ticket did not understand the restrictions of the ticket.
In addition, if he needed some assistance because he doesn’t speak English well, whoever booked his ticket needed to contact the special assistance department at United and note that so he could have received assistance at the airport.
None of us work for the airlines- we are all volunteers here and are explaining why he was charged the bag fees. Please refrain from insulting those assisting or we will have to close the thread .
If you feel he was discriminated against, you should write to United using our company contacts or contact a Civil Rights Attorney.