I think the sympathy question is interesting, but difficult, because it's an emotion which makes it very difficult to quantify.
I am close to a person who is fond of saying; 'I have no sympathy with that...' and blustering on.
I think, if pressed, she probably would have some level of sympathy for most things.
In this case, I think it's hard not to feel sympathy for Reeva, who did nothing wrong, and who had the right to be where she was. I think it's also fairly easy to imagine sympathy for a child who through misadventure had found himself there. You think of the life lost. I think it's also possible to feel sympathy for an intruder bent on killing/raping those in the house, but this is less than the others. It's hard to say precisely what you might feel in this case though, because that intruder wasn't there.
However, I think it's also possible to bundle all that emotion up and put it aside and think dispassionately about the ins and outs of it and say that despite having less sympathy for the potential rapist, it still feels wrong that they can be killed without a trial. There still needs to be the shown attempt that you tried not to kill the person.
It is very hard, who you feel sympathy for - and the reasons you feel sympathy for them. It's different for each person, and it changes over time. I felt no sympathy for the drunk, uninsured driver who totalled my car when it happened. It was much later that it occurred to me that I know sod all about him.
I feel lots of sympathy for people who choose not to speak to their parents, because that's my position. Other people feel more sympathy for parents who's children don't talk to them, because they know how awful it feels.
I'm not intending to preach or suchlike, but I think it's really hard to challenge people on how much sympathy they feel and for whom, because it's entirely subjective and intensely personal.