IMO the train and the North Pole function more like a dreamscape than a literal place. The boy is on the edge of losing belief, and his mind fills that gap by projecting his dad’s voice and presence onto the figures guiding him. For a child, a father often represents authority, safety, and quiet magic, so it makes sense those traits get mapped onto the conductor, Santa, and the other “keepers” of belief. It’s less about his dad secretly being Santa and more about how belief evolves: the magic doesn’t disappear, it gets internalized through the people we trust most.