my experience which is similar to what is in the game
I'm betting it didn't involve a software bug causing a mind-reading spirit to reveal things that no one would ever have known otherwise. (Please note that I'm not in the least asking you to tell me what it did involve, as that's a very personal matter and not suitable for this topic.)
Either you can choose to hold his sins over him forever if it suits your worldview, or you move past it based on your experiences with him.
This is pretty much my conclusion after reading the many pages of debate that followed Kallen's original post.
Kallen, your posts have made it clear that we can't change your views about Blackwall, unless you're willing to reconsider your views about redemption, and you don't seem to be. Either you think that people who do terrible things can realise the awful things they've done and become better people by making genuine efforts to atone (in which case the Blackwall of today, not the Rainier of the past, has a chance), or you think that once a person is tainted by evil, they're tainted forever, and no good thing that they do thereafter can redeem them even slightly (in which case he'll never be anything but garbage).
It's really up to you to decide what to think. All I can say is that I'm not so perfect that I'd want to live in a world where redemption was impossible.