Did they really?
Or did they just post random crap on twitter in relation to a person named Nico Viljoen who happens to live in the same area as this guy, and even those postings are not guaranteed to be accurate. Nico Viljoen will be a relatively common name if you ask me.
I say this on the basis that another person by the name of Nico Viljoen has been getting death threats, so clearly their "doxxing" hasn't actually been all that accurate.
The only man I know who was mistaken for Nico Viljoen and subjected to death threats, which I happen to think is going overboard, is some guy called Jacque something or other. I don't recall anything about another Nico. Where's this link you're reading from.