You're looking at the problem in a "spherical rape victim in a vacuum" sort of way. There is a whole bunch of context that doesn't fit into your hypothetical.

Sexual victimization is not just another crime. Most sexual assaults are carried out by partners, spouses, and relatives. So the victim has a complicated mix of shame and conflict of interest. Not to mention that a raped women is often viewed as "damaged goods", and a raped man as a sissy, so social status is at risk too.

Society re-victimizes sexual assault survivors and attitudes of victim shaming contribute to this. What victim shaming doesn't do is prevent people from being sexually assaulted. We know this because if victim shaming could reduce sexual assault, rape would be rare.