"You're a time traveler, are you?" he asked. "That must be quite interesting -- being able to explore different time periods, different worlds since you said exploring the universe. Must get to meet a lot of new, interesting people." Clark thought he might like exploring the universe, if he'd had the time for it.
He didn't ever seem to have the time for it back home, though. There was always something that needed to be done. Which he truly didn't mind, but it didn't leave a lot of time for other things.