He wants to bolt, but his panic is all internalized because he also wants to stay put, so if he just keeps following her vein of conversation, maybe his panic will subside. (He's not that optimistic, but he'll take what he can get.)

"Got any whims? Earth, other planets? Terrestrial, aquatic? Particular part of time?" He shrugs, jostling her slightly. "Could always randomize things."