at this point in the story , he just wanted an admiral that was clearly a villain but his monologue was just woefully exaggerated,.
To me this is the proof Oda is speed reading
Powerscaling aside how can you compare the introductions of the other Admirals and their justice to Aramaki's?
Kuzan got a pre-arc + Ohara flashback
Borsalino got the best introduction
Sakazuki got the whole war
Issho had the entire Dressrosa arc
Here Oda brought him for 3 chapters and remembered he needed to characterize him before he dipped