Well now you're aruging semantics. Knowing the difference between right and wrong is something you learn from an early age. Reacting to robbery with murder is a wrong, and if this thread didn't exist and we created a new topic titled 'should you kill someone that robs you', if people are being honest, the answer would be no. Because we know what is right and what is wrong. And that's what takes us above the scum that we try to enforce law on.
Ultimately you are not a right person if you feel that killing someone is justification for having material possesions stolen. And that is what has happened here. The article clearly tries to steer you in the direction that the sheep on this thread have taken, stating how great it is that he got what he deserved and that the guy shouldn't go to prison blah blah blah (sorry guys but really?). If you use your head you see that he was charged with murder, which means that it has been determined by professionals (fortunately not people that work for the daily mail) to have been a situation outside the realm of self defence.
It's far too easy to be drawn into that article due to the way it is written. The only fact you need to take from it is the word murder. The guy isn't a hero, he's a murderer.