There is justice, and there is injustice. Social justice is a way of dressing up injustice so it looks more palatable.
You would never go out and beat, harass or otherwise victimize some innocent person would you?
That would be an injustice.
Ah, but you see, he's not innocent, he's an oppressor (even though he's not bothering you) he's an evil racist bigoted hater (even though you've never talked with him) and he needs to pay, amirite?