Imu is the ultimate villain of the manga… you seriously think that Oda implemented a literal king of the world who destroys islands and stands for the opposite of freedom… and you literally don’t expect him to fight luffy… it’s like people expecting luffy not to fight Enel because Wyper vowed to kil him.
Yet you say sabo must fight akainu which he has no personal feeling to him.
Luffy say he will fight jack and big mom , yet it didn’t happen.
IMU is guy who hide shadow , . Don’t compare him to Enel who rule skypedia publicly.
Buster call already have destroyed island before.
If marine force simply vanish, can world government rule 800 years without marines forces ?
IMU can be ulimate villain of arc but luffy don’t have to fight him .
Big mom is ulimate villain of whole cake island arc , yet luffy didn’t fight her.
spandam is ulimate villain of enies lobby arc. The guy literally command cp9. Yet luffy didn’t fight him.
The reason I say dragon and sabo will fight IMU because they knew true enemy now.