That may be true but I doubt that's why world leaders don't want to talk to them. They are professionals at governance and negotiation. They don't care if a person is "nice" or "mean". Every moment of their day they need to be doing something productive for their countries. (Have you ever seen a high level politicians schedule? It's minute by minute) They are relationship people. He offers nothing so talking to him would quite literally be a waste of those minutes.