Your entire post hinges on the belief that him getting arrested, going to prison, etc is how he starts to "reform."

I can tell you this, though:

Many countries do not have a prison system whose main purpose is to rehabilitate the offender. In many prisons, inmates convicted of rape get assaulted, both physically and sexually.

We also know people who have been sexually abused sometimes go on to reenact that abuse, ie being sexually abused increases the chance of someone becoming an abuser. I imagine the risk for him is higher since he already raped someone once.

The OP's first post described someone who treated her with respect, love, and compassion. It describes someone who seemed to demonstrate remorse for past decision. In her first post, she wrote that he stated that he realized how fucked up what he did was and decided to make an effort to become a better person after that. And it sounds like he did become a better person, ie he "reformed." If he is reformed, then going to prison doesn't protect anyone, nor does it further "reform him" either.

So, I really don't see what him turning himself in does. The police will have to contact the victim, who will then be in a situation where she may be reliving her rape, being questioned about it, etc. Then, he risks possible physical and sexual assault in a prison system that is most likely punishment focused and not rehabilitation focused, and then he lives with the label "sex offender" and can never truly move on with his life, get good employment, etc.