second of all
sabo is guy who got almost killed by celestial dragon abd IMU .
‘Akainu is not only one who do absolute justice. There are more crazy marines like greenbull,etc.
Heck it make sense for sabo to fight IMU because he literally saw soneone sit the throne .
Revolutionary enemies are celestial dragon, they want remove celestial dragon controlling world government. Defeating Akainu does not mean celestial dragon is defeated .
Sabo does not hold grudge against anyone on ace death , otherwise he would beat Jesus burgress badly .
‘And Blackbeard is only one bring Ace to marineford, by your logic sabo should beat Blackbeard to avenge Ace , not Akainu because Ace is scheduled to die on marineford by sengoku .
Did you think luffy would not get mad at Akainu for killing brother in his own eyes ?
Luffy got sprit broken by Akainu.
Luffy got scar from Akainu , like zoro got scar from mihawk .
Sabo fighting Akainu is same logic as shyrui fight mihawk and beat him or Kidd beat shanks .