"Well, there's a reason I carry a communicator with me off-world," he answered. In case of emergency, call to the ship and beam back over. It worked alright for Sulu; there was no reason to believe it wouldn't work alright for him as well. Maybe Kaylee's world was a different level of potentially dangerous than, say, twenty-first century Cardiff where Jack and Ianto were from, but that didn't mean there was any reason not to visit, at least for a little while. Although, in all honesty, if he did find himself in the middle of something in Kaylee's world, it wasn't entirely likely that he'd just skip off and leave them to fend for themselves.