It does lead to questions unanswered.
What was the shooter saying to the woman in the car?  She got out for a reason after a (somewhat) extended conversation in the car.  Other than the guy being a dickbag over her parking there (notice he wasn't in a parking spot either) what transpired to get her out of the car?
Did the victim (yeah, he's a victim) overhear something that caused that reaction?  If a man told my significant other he was going to beat the crap out of her for parking in a handicapped spot, I'd surely take issue with it. Probably not to the physical level, but you'd bet I'm getting between him and my family.
Did the victim say anything else after backing off?  "I'm going to eff you up" could be perceived as a threat even if he wasn't moving.  
This guy (seems to be a recurring theme these days) was on the radar with possibly violent encounters before.  It seems rather odd the Sheriff dismisses his previous encounters as "not being relevant."  Sure seems relevant now.
He blindsided him and I'm not going to call that one a "violent" anything.  It's not like he ran into him.  He walked up and shoved him.  No punches, no kicks, no running start.  Just a shove from a standing position.