I'll be honest, I think restorative justice is an absolute meme. We can't even implement it when people make bigoted statements on the internet, they usually get banned or disassociated with for good reason, yet people think we'll be able to reform heinous abusers under anarchism.
I'm not saying it's impossible but I think it would account for the minority of cases. I don't believe in prescriptive forms of justice and think it will vary depending on the costs of taking action, but in all likelihood, people who commit the worst offenses would have their identities circulated, get beaten up, or in extreme cases, wind up getting shot.