I saw nothing that said the cat attacked him a second time.
If he went home, then came back to beat the cat to death, he's a monster and should be locked up. The woman should not have had the cat loose, and should have put the cat up after it attacked someone. BUt HE killed it.
There is NO way that "prodding" a cat who is trying to attack you would stop it. Obviously you've never dealt with a attacking cat if you think so. But did the cat even approach him the second time?
If the cat went for him, he's well within his rights to defend himself, but not to the point of beating it repeatedly. If he hit it, and it died, then well.. it's very sad, but the cat attacked him.
The story is written with a great bias towards the cat's owner being an innocent victim, and she is at fault mostly. Depending on the actual circumstances, he is at fault for killing a animal after the attack was over, or defending himself during a second attack. She is at fault for any injuries he received, and should be cited for the attack, and for having a uncontained pet as well.
I didn't see what happened, and I certainly can't say what happened. But if he left, then came back and killed the cat, he's a wacko, and should pay for a unwarrented attack on a pet.
If he walked by your front yard and your ball python bit at him, because you foolishly had it laying outside next to a sidewalk, you could probably see him jumping or hitting at the snake. BUt if he left.. then came back later on, and beat your python to death, when it was just laying well away from the sidewalk, just because he was angry it bit him the first time.. then it's a horrible crime, because he WASN'T defending himself.