It is irrelevant what Rosebaum did in the past. It does not matter to the situation at hand. It doesn't matter if he raped 100 little boys and wore their skin ... his wrongs that he did in the past DO NOT JUSTIFY Rittenhouse's actions during that night. You may find it disgusting, but that is how the legal system works. We aren't "Defending a pedophile" we are upholding the law.
The only thing that matters is the events that happen the night Rosebaum was shot by Rittenhouse ... that's it.