So basically the NRP can behave however he likes but the RP should continue to pander to that behaviour in order for the children to see him?
My ex has already abdicated all his responsibilities, he has already abandoned his children, he has already relegated his relationship with them to a weekly phone call which he often cuts short if he has something better to do (but woe betide me if we are a minute or two late for that phone call), I already raise three children including two preschoolers completely by myself including 3 mile bus journeys to and from school three times a day, there is no way on this earth that I am going to start taking 6 hour train journeys at a massive cost to my already painfully stretched budget in the vain hope that they might actually see him. That is his responsibility, it is not mine. If he wants to arrange a schedule of contact visits then he is welcome to do so, but it will be at his expense and on his time.
FWIW, he was a very reluctant NRP. He would have much preferred we remain together, he get to see the children everyday and I do near enough all the work both in and out of the home. He thinks I am an evil person who has driven him away and taken his children from him. I expect he'd happily have the children live with him as long as his new wife was there to do all the work involved. Actually, if I emailed him and told him I was bringing them to visit he'd more than likely tell me I had no right to dictate to him when he sees his children, because that's the kind of mentality he has. Similarly, if he emailed me and told me that he wanted me to bring them to see him and I said no, he'd tell me I had no right to dictate to him when he sees his children...
To return to the OP, obviously neither I nor no-one else knows why the relationship broke down, why the father moved away, how he views his contact with the children etc, but I stand by my response that in moving away he took on the responsibility for travelling back to his children's local area to visit and/or collect them for contact visits. If he didn't want that responsibility then he shouldn't have moved away.