DAMN IT COULD BE THAT IMU AND JOYBOY WERE FRIENDS BEFORE BUT SOMEONE ELSE MIGHT'VE SEPARATED THEM AND TURNED IMU AGAINST JOYBOY AND JOYBOY CONSIDERED IMU AS A FRIEND SO HE DID NOT FIGHT HIM 800 YEARS AGO AND LOST, EMETH COULD BE SAYING SORRY TO JOYBOY CAUSE HE COULDN'T SAVE IMU FROM GETTING CORRUPTED OR SOMETHING. IDK its just a wild theory I could be wayyy wayyy wrong but I didn't expect Luffy to be actually cautious of Imu or maybe eve scared and also didn't expect Imu to make that face