Suppose Satan is the only creature in existence and Satan sins gravely through pride, does not repent, and goes to hell forever. Hell is a punishment from God. Now in punishing Satan in this world, God does something good to creation, since God does not do anything to creation that isn't good.
But every good is a good for someone. In that world, however, there is only God and Satan. So for whom is that punishment good? For God alone or for Satan alone or for both God and Satan?
It does not seem that the "for God alone" answer is satisfactory. For God, considered on his own, has an unchangeable perfect flourishing. Additionally, there is an extended well-being that God has when those that he loves receive goods, but that presupposes that God isn't the only recipient of the good. Besides, surely, when God acts in creation, he produces good effects--he is, after all, omnibenevolent.
Hence, the punishment of Satan in that world is good for Satan (and maybe for God, derivatively via extended well-being).
But if it is good for Satan in that world, why not in ours as well?
And why is it necessarily good for Satan? Presumably because in general punishment is good for those who justly receive it.