It wasn't a hard read. Trump sees Carney as a banker and for someone whose whole world was real estate in New York in the 1980's that is EVERYTHING. He is dazzled by him but he will never be able to match him and the power he holds over the prestige Trump lusts over. He uses this to corral Trump to focus, if only for a news cycle and then lure him with real world opportunity and since Canada has all the resource cards he will always have a winning hand.