Nikko only knew about Team Avatar saving the world and stopping the Fire Lord at the time, so he was slightly amazed to hear about what the others had been doing. As Jaya had say, a city for all four Nations sounded like a paradise. A place for everyone to be together, regardless of where they came from or what bending they had. He only hoped that the city would be a success, and would not became another battlefield. 

"Well, thanks for your time." Nikko said to Katara. "I'm sure that you have other things to do than to show two people around. Thanks for the hospitality!"