It's an annoying answer, but Jotaro believes the guy's being truthful and so he won't hold the brain-shaking or annoying twenty questions garbage against him. He doesn't really have the energy for grudges at the moment, and the fact that this guy looks to be as worn out as Jotaro himself has felt since Cairo is working in his favor. Being straightforward is just... Easier. Most of the time, anyway.

"What about your name? That alien too?" He's gonna assume his host already knows his and so he'll be skipping the pleasantries unless it proves necessary.