He got surprised by Bepo and ultimately was just fine
And again, he's clearly not at his peak yet. He's going to be above Xebec and Davy Jones by the time he fights Luffy
Imu is already at his peak and has been alive for over 800 years, the fact he's getting worked over by injured old Gaban and Hajrudin to this degree is kind of sad. Oda needs to give him a big buff if he wants him to be the final villain or even the second to last villain