But his life wasn't in immediate danger?
Self defence can also be used when defending the lives of others...
He opened the door slightly and saw a man standing over his wife with a gun to her head. He locked the door and grabbed his firearm from the safe. He could hear more screams and then shots. From a bedroom window overlooking the front door, driveway and balcony, Maharaj fired shots at the robbers
https://www.issafrica.org/pubs/CrimeQ/No.8/duPlessis.htm
In determining whether a crime victim acted reasonably, the courts judge each case on its own merits. Certainly, an owner who is confronted by a robber is not expected to abandon his property. He is entitled to protect it, and the court will consider all the circumstances2 when deciding whether the means of defending the property were reasonable.
This right to self-protection can provide a defence to a charge of assault or even, in some cases, murder. Our law allows you to defend yourself, another person, your property or the property of another against a current or imminent unlawful attack.3 When a person pleads private defence, his claim is that the injury he caused was, in the circumstances, lawful and permissible.