two-volume book published by Taschen, “Arnold.” The centerpiece of the sold-out evening was a wide-ranging conversation between he and the book’s editor, Dian Hanson, followed by a 3D screening of the film. Today, the actor, activists and former California governor credits Cameron with coming up with the “brilliant idea” of having his Terminator be a protector instead of an assassin in his 1991 sequel. But he corroborated Wednesday previous interviews with Cameron (and expanded on revelations he shared in his Netflix documentary, “Arnold”), saying that at first, he was frustrated with the plot twist.