A lot of people simply don't realize how important this encounter between Imu and Gaban actually is; it’s not just a standard fight scenario.
For the first time, Imu is facing someone who knows the true history of the Ancient Kingdom, Joyboy, and everything else. Imu is going to ask everything about the One Piece; he’ll want to know exactly what Gaban knows.
And we know how insanely Imu reacts to anything related to Joyboy.
No character in Elbaf could possibly have a bigger death flag right now. Loki and Luffy have been defeated, who is left to stop Imu?
On top of that, in this chapter, we see Imu actually mocking Luffy; just imagine if he were to kill Gaban right before Luffy's eyes...
I have a really bad feeling about Gaban; things don't look good. I just hope that, at the very least, he goes out with a bang.