Fujiora is actually just right outside the palace. It wouldn't be a stretch for Zoro to get lost and stumble upon him to save franky or something. Fujiora could just walk into the palace to confront DD and stumble upon Zoro. Zoro would one- shot Lao G. Who really knows what Oda is planning to do with Zoro at this point. All we know is that he's not out of the game.
He's actually in front of the Toy House Franky invaded.
Compare the backgrounds.
http://www.batoto.net/read/_/212590/one-piece_ch732_by_powermanga/6
http://www.onemanga.me/one-piece/743/11/
Also, Zoro would need to use the lift to reach the Toy House for Franky, and Lao G just happens to be guarding the lift.