My understanding is that both Ricca and Accardo wanted Giancana. He had proven himself many times with his ability to make money and willingness to kill.
Giancana was a great moneymaker. His tenure was good and bad. Good times and lots of money for awhile, but a terrible time to become boss. Lots of heat.
That is very possible that both wanted him in power, but like with Gotti it's hard to see how guys will act when they have "the power" now. While I'm sure Momo showed some actions that he was able to act out like he did but I seriously doubt Ricca/Accardo would have bumped him up if they knew he would have done what he done. They were just too damn smart to put an idiot there and while Momo had a ton of power it seemed they also could have put him there to make sure they could try to control him and figured out they couldn't. It's easier to clip a guy in power when he is suing the feds than when he is rising up and is well respected.
