It was obvious from Zoro's expression that something complicated was going on here, not to mention from Zoro's asking the question in the first place. He didn't think Zoro would believe the lies they told here; he didn't think anyone in the crew would. But it was a little confusing, thinking there might be another world or another version of them or something, since after all there were versions of them from different times and things popping up. Usopp figured it could all fall under a simple rule, 'if the Institute says it it's probably a lie,' but that might be overreaching.

At any rate, he'd answered with all honesty. Whoever she was, it disturbed Zoro to see her like that, and that disturbed Usopp a little too. Like a universe where I hurt Kaya somehow...

"She's a fake," Usopp said with as much firmness as he could, even though Zoro had obviously not been addressing him. He wasn't sure he meant it just for the woman in the photo either, but for the Kaya who'd supposedly put him here, too. All of them.