The way I see it, he has got off on a technicality. Masipa said that OP was an unreliable and untruthful witness - but that doesn't make him guilty. Nel hadn't proved his case for murder beyond reasonable doubt, and Masipa said that where an alternative version of events is deemed reasonable, or even possible, by a court, then the court must acquit.
Personally, I fell OP's account of events is so full of holes as to be completely unbelievable (unless the man is an aggressive, paranoid imbecile....oh, wait...)