I do understand why some people don't understand such a blind panic. But all the things you have mentioned that he didn't do are the very things that some of us wouldn't do when in a blind panic. Yes he has a history of different responses but surely you understand that people don't have a list imprinted on their brain of how to react in a particular way at all times, in a panic situation. I think his past escapades are indicative of how he behaved that night, a disaster waiting to happen.
Most of us have a default fight/flight mode. I know when I get a fright I get extremely angry.
Fight. Flight. Freeze. Fawn. These are acute stress responses to fear and terror. A burst of adrenaline prepares our bodies to run, hide, fight or placate. Pupils dilate. Digestion slows. Muscles get more blood in preparation for action.
The name of the response (fight/flight/etc) describes the dominant emotional and physical reaction a person experiences in response to fear and terror.
If we experience a fight reaction it means the dominant emotion we feel in response to fear is anger and aggression, and so we fight. Flight means the dominant emotion is panic and we will run away and leap over a tall fence to escape. Freeze means you can't move. Fawn means you try to placate the aggressor.
Let's look at what OP tells us about that night.
OP says he felt panic and terror and fear. These are the dominant emotions we expect in either a freeze- or flight response. So, if we believe him, we'd expect him to freeze or run away. Because he never mentions feeling anger or aggression. So, by his own testimony, he did not experience the fight response.
But look at his actions. He got a gun. Moved toward the danger. Shot the so called attacker. He fought. A fight response.
The point is that there is a glaring discrepancy between what he tells us he felt that night and what he actually did.
For some reason he does not want to admit to feeling any anger or aggression. Which, if you believe him that there was no argument between him and Reeva, is a very odd reaction indeed.