The man beamed back at John Dawlish, and nodded his head to confirm that he was inface the very Mr. Scamander that John thought him to be. "Yes, Good, Hello. I am Mr. Scamander--call me Rolf, please, yes? And you are John?"
Part of his excitement was do to the fact that he had guessed this man to be Mr. Dawlish. He'd seem him walk in and the way he'd looked around quickly before looking to the waitress had said, in Scamander's eyes, so very much about him.
Rolf had the terrible habit of comparing animal and human behavior. (Not always in a flattering way to either species, though it should be noted that the animals did complain far less about his observations.) The way John moved, the way he spoke, and the way he approached Rolf with a kind of timid determination said to Scamander that he was a mostly independent man who was was probably very close to his mother at one time but was not anymore--and he felt guilty about it.
He was also a secretive man, probably didn't trust as easily as he pretended to--keeping a chair and table between himself and the man he might just be living with said as much. He didn't exactly exude warmth or friendliness, but that was just fine with Rolf who'd always found it easier to be friendly to things with paws, furs, and scales then with people. People made mistakes, people were wrong and hurtful. A dog couldn't make a mistake.
Scamander got to his feet (slightly against his better judgement) and extended his formal hand out to the other man. "Please, I hope you will be sitting."