I think that it depends on the type of rapist. There are the so-called anger-retaliatory rapists whose main object is to cause pain and degradation to the victim and who may escalate the rape to a deadly attack if challenged. Unfortunately the "correct" response to an attack usually needs to be determined rapidly in a very uncertain and fluid situation while being subjected to a great deal of stress, so it's not always clear what the correct course of action is -- another sad aspect of victimization.