Aiuppa and Cerone didn't take over by killing anyone, they took over by death and imprisonment of the Taylor Street crew. Giancana left to escape harassment from the feds, Alderisio and Battaglia were jailed and Buccieri died of natural causes. The only guy you can say they whacked on their way to the top was DeStefano and that was only because they knew he was nuts and was fanatically loyal to Giancana. Hell, Blasi was as close to Giancana as anyone and he ended up being direct with Aiuppa and Cerone for many years after they took over. Chuck Nicoletti was killed because he was suspected of being into drugs and grumbling about the bosses while Chuckie English was killed for basically the same reasons sans the drugs. Everyone else aligned with Giancana was either allowed to stay on or was quietly shelved. All in all, I think saying that Aiuppa and Cerone shot their way to the top is a bit of an exaggeration.