Tidus says nothing as Nita's attentions go to the engine room, the train, whichever it is (if they can't be called the same), looking back off to the rest of the store carriage. Waiting for whatever it is that'll come.

Nothing is what Tidus suspects (when has it ever been anything else in these communication attempts?), but he's not sitting there playing guessing games. Remembering the chill of the platform, the people who left earlier that day.