Anyone who values human life so little deserves what they get too.
The rooster was just defending itself. If a man was assaulting you and you killed him while defending yourself, I would say the same thing, that he deserved what he got. If he hadn’t been forcing the rooster to fight, he wouldn’t have been injured and he’d still be alive today. Karma has a way of coming back and biting us in unexpected ways, in this case it was a rooster’s beak.