I don't think he's being a phony about it. How would it help him if he went into that meeting and clashed over everything with Trump?
Yes. There's no reason for him to talk about anything that isn't related to his upcoming job as Mayor of New York. He isn't involved in the federal government, but he does need money from Washington, as every Mayor of New York does. And since he has a great deal of talent, he decided not to bring up anything that wasn't related to New York and what he wants to accomplish there. And that's what made it work. He was totally on topic.