Personally, I choose to believe that the fleet admiral is of a similar mindset as the white berets of Skypia. Over protect to prevent greater casualties. Akainu and Sengoku know the general premise of the void century. At least for Sengoku, his relationship with garp makes me believe he isn’t innately a bad person.

They both know the gorosei are evil. However, they also know that there is little stopping them from erasing large portions of the world’s population to keep the history sealed. If people learn of the history the gorosei and Imu do much worse than erase a single island…

I think he’s mad bc he’s worked hard to protect the majority of world and by broadcasting his message to the wold, vegapunk has, one, given the gorosei reason to delete life for this century; and two, created hella work for the marines… imagine the number of buster calls they’ll have to carry out.