Im not him but can I answer?
If yes then I honestly believe what he did was wrong. We don’t know what this stranger would’ve done to the lady in retaliation for this white knight trying to save her, abusive relationships tend to become far more violent when someone tries to “fix” it. What he did was far too reckless as that Chris Brown could’ve been most likely armed or with some sort of weapon, jumping in blind as if you’re Superman will solve nothing. Police are there for exactly for that reason and are excellent in this sector of handling, remember you are a stranger that knows next to nothing about these people, they likely won’t even be happy that you intervened; statistics show a large sum of abused partners to stick and agree with their abuser, even if you beat up the guy she would still go back. I’m not suited for this, I’m not good at mental health issues neither fighting strange men who are clearly over compensating for something and in my experience means they will be packed with a weapon.