I have heard people say, without hyperbole, that they think that rape is as bad or worse than murder. Many rape victims also seem to feel that - 13% of rape victims attempt suicide. Think about that. These are people, a large number of people, who genuinely believe that it's better to be dead than raped. That's a problem, a big one, and it's a problem of perception. The courts only reinforce this, if they're handing down life-ending sentences over rape offenses, and that feeds the problem further.
I've made this argument myself, and I do think that murder is worse than rape, as you do. However, our prison system is not really about rehabilitation. I wish that it were, but it is not. Given that, life sentences for rape seem reasonable. If the goal is to reduce recidivism, we can't permit them to get out of prison, since our prison system is designed to increase it.
What needs to change most is our prison system, which increases violent crime in our nation.
Back to TFA: molestation isn't rape. Without reading the article, I'd guess based on the sentence that the offense of the guy in question was pretty small. Maybe a grope on the train or something, happens pretty often on those crowded Japanese commuter trains.
And that's why he shouldn't be allowed to cover up his record. If he did the crime, then he's part of the problem and that being known is part of the overall picture of solving the problem. If he didn't, then he has an opportunity to say that he was found not guilty or whatever they call it over there.