I think that Liam Lacey may misunderstand what this was about. Schneider has said years ago that she had felt "raped" and "manipulated" in the scene and what she was objecting to was the use of the butter, which was introduced by Brando and Bertolucci at the last moment. I've not seen the film myself, so I don't know how graphic this is, though it is certainly one aspect of the film that has made it into popular culture. The outrage is over the fact that Bertolucci deliberately and admittedly went out of his way to humiliate the actress, not just her character, as a way to get more impact into his film. The bullying that went into the scene is what is at issue.