You are obligated not to keep pounding someone until he is dead. That is what Junta did. That is what the multiple witnesses testified. That is what the jury heard. That is what the defense could not dispute. That is what makes it manslaughter. That is why Junta is where he should be.
I simply disagree with you about what made this manslaughter. I suspect what really made this manslaughter was that the prosecution was careful to pack the jury with, little, politically correct zombies. Wish I had been on it. If I had been, given all I've heard (and I heard much of it), I would never have agreed to a guilty verdict.