Atma, when a little observing this sickness and treating of it, that leads even to violant aversion of people thought to be related or in jugde of the phenomena, had to think, look, on cause and effect.
It's like people, not familar with the Dhamma, with no goodness, treat animals who transfer sickness. As if they would have the intention to harm, they are killed like if no way to let them live, brutal.
It would be no wonder if such effects from deeds would match even humans. Think how many people simply kill mosquitoes, rats, dogs, pigs...
It's not a wonder, having acted, having such habits, that one meets such aversion himself.
So aside of giving conditions and further bad actions for one, by acting merciless, one should not harm any being, not to speak of harm of innocent, for such is the highway to hell.