"I only really knew Gohan -- the other halfling. My father and Goku died when I was really little. I don't remember them. Not the ones from my timeline, anyway."

Trunks has grown so used to casually passing from timeline to timeline that he's forgotten that mentioning time travel isn't exactly the norm for everyone. Not everyone is a Briefs, has Bulma for a mother, or inherited her intelligence. Just because he can repair a time machine doesn't mean the people of Rebekah's world even have the ability to build one, let alone fix one that's broken.