Nah, all Gaban can really do is show off FS I guess. He avoids DR with that, but Imu has some pretty big AOE attacks iirc, so it shouldn't matter much. He's already said Imu has Haki like he's never even felt before, and Shanks was hyping up Imu as an unstoppable opponent that no one could take down in the same room as Gaban.(The Roger pirates are the only ones who even knew about Imu, so Guess who Oda was talking about)
Loki also got several chapters of fighting Imu, while imo Gaban is brought in for more lore related reasons. More like Marco in Wano, he has knowledge about the villains that no one else does. I don't think he can get the Rayleigh role of fighting the villain and being the star of the arc.