It's being a coward. I've seen it happen with friends, tons of situations. Hitting a person who doesn't expect and than taking off is a bitch move. Happens all the time. Half the people that do it .. say themselves it's a bitch move. Sometimes emotions get the better of people and that's the result and that's fine but still doesn't make it not a bitch move.
It's not a fight. It's just hitting somebody. A fight is when two people who are both willingly ready to throw down go at it.
As someone who has both done that, and had it done to me, I can tell you from experience it's a natural reaction when you are in a crowd/brawl. One on one fights are totally different from punching someone with an angry group of people around. You can call it cowardice if you want, but it is a normal human reaction.
Sarcastic those pictures mean nothing. Korver is trying to avoid the foul especially since the player is already in shooting motion. You can even see Finley leaning towards him. I know you're better than this.