My recollections were that Joe flipped to avoid the death penalty on the Pizzolo murder.
He also got to keep the house for Mrs Joe (nee Vitale).
Releasing is a stretch.
MORGAN: Why didn't you fight him at the park if you wanted to? I'm not goin' now, I'm eatin' my snack. CHUCKIE: Morgan, Let's go. MORGAN: I'm serious Chuckie, I ain't goin'. WILL: So don't go.