Yekke2, so we agree that rodef isn’t relevant. We’re not discussing killing him (as much as some people would like to), we’re discussing reporting. I’m not sure why you brought it up.
Of course, I am referring to locking up the abuser. He is deserving, and he brought about the situation that locking him up is a deterrent through his own actions.
I similarly wouldn’t support locking up an accused abuser who is actually an innocent person, though it might be a deterrent.
The motive isn’t revenge; the motive is prevention, but we still need to differentiate between the innocent and the guilty.
And I think that this is the bottom line of what the OP is driving at: is punishment/revenge sufficient reason to report/ lock someone up, or does there need to be a benefit? If there does need to be a benefit, which type of benefit might be excluded? These are theoretical questions, and they may indeed ve of no practical import.