There is a difference between flights being delayed and a student being able to walk around campus to get to the nearest cafeteria. Your S is going to need to walk to classes and activities and the cafeteria during the winter…Thanksgiving time usually does not feel like winter so it should be ok, and it does sound like the shuttle runs daily…of course taxis, ubers and lyfts are always around too.
I live in Chicagoland and attended Northwestern…every year there is a program where alums host the many students staying around for Thanksgiving…many NU students stay around, including most of the internationals…perhaps UC has a similar program?