gone I think your analysis is seriously fallacious.
The State didn't give up. From the indictment itself it is abundently clear that they knew the case for him knowing it was Reeva would not be easy to prove. All the evidence was circumstantial - although most of it was compelling.
"Error in persona is not a defence to murder" it said on the indictment. And they were right to say that....the SCA vindicated them and agreed.
The fact remains that, whoever Pistorius thought was there, he was still a murderer because he was not under threat, had no credible reason for thinking he was, used disproportionate violence (four shots) and ignored all of the guns laws that he was schooled in.
The very fact that SA has a problem with violence does NOT excuse any person for behaving as Pistorius did....in fact, it's exactly why the self defence laws are so very stringent. Violence begets violence.
That man heard a vague sound in his bathroom. Didn't trouble to properly ensure it wasn't the person who shared the bathroom with him...simply grabbed his gun, headed to confront someone, heard a noise and then fired four times into a box.
If that is not murder, I don't know what the hell is.
And, frankly, if you think the most likely explanation those horrific, haunting female screams four people heard at around the time a woman got murdered were made by her male murderer hobbling down a passage in the still of the night to confront an intruder, then I have a bridge you might like to buy.