This is the problem....we know nothing about the attacker... notice how we know nothing about the guy who physically assaulted a stranger over an argument over a parking space? We know about the victim...because everyone wants to crucify him...but to just walk up to a stranger, and shove them that hard, without batting an eye shows that that guy is likely used to violence.
Did he "just walk up to a stranger, and shove them that hard" or was it instigated?
I'm not speaking in legal terms, I'm just pointing out that your description makes it sound as if the guy walked up to a random stranger for no reason and shoved him to the ground. According to the story the shooter was arguing with the wife about where the car was parked. Who knows what might have been said? Describing the man as "likely used to violence" seems to be getting a lot more out of limited information than I can see.
Also, the article gives the names of the shooter and the man who was shot. It gives their races. It gives their ages and it says that the shooting victim was a father to 3 children. It gives the name and age of the girlfriend and the ages of the 3 children. It tells us that one of the children was named after his father. The article even describes where the couple met. I'm not sure where you get the idea that "we know nothing about the guy who physically assaulted a stranger over an argument." The article isn't overflowing with information, but there's some about all the main parties involved.