Wild Bill was murdered for a few reasons. One, the Persicos were worried that he was going to stage a coup and take over the family. Cutolo did have a lot of supporters and underlings. Two, Cutolo allegedly called Persico a rat for acknowledging the existence of the Mafia in the 1986 Commission trial, which angered Persico. Lastly, Cutolo sided with Vic Orena in the war. The Persicos decided to demote Cutolo to soldier as punishment but then chose to kill him a few years later. I don't know if they were planning to kill him all along, or just decided to do it. But grudges are held in that life so I am certain a lot of Persico people wanted to see him go from the start.