It was actually a comment Dunne made about Jean-Claude that finished off Dunne's faltering career in Hollywood. Mengers became infuriated when the Hollywood Reporter quoted Dunne as implying that nepotism, not talent, was the reason Jean-Claude was hired to write the screenplay for Ash Wednesday. He compounded the insult by referring to Sue's weight problem. Mengers, then at the height of her powers, made certain Dominick Dunne never ate lunch in Hollywood again. Or, so she thought. How was she to know that the end result would be a dazzling new career for Dunne that would enable him to dine out anywhere he damed well pleased.
Read about it in greater detail at A Boat Against the Current.