They do when their god is the one doing it. Is he not incapable of doing anything that is not merely justified, but good?
Not all evil involves moral evil. For example: we experience hurricanes, tornados, forest fires, droughts, earthquakes, etc, as evil. Yet it turns out---those things we experience as bad---are actually seemingly necessary for life on this planet to flourish. Thus----those things we experience as bad, seem to have a greater purpose in the long term---namely----maintaining life on this planet.
Thus, I would suggest that it is impossible for God to commit a moral evil. Sin is impossible for God. This does not entail that God cannot do an action that is regrettable but necessary in order to carry out his larger purposes. And as God created a world whereby, He endowed human beings with freedom---sometimes people are going to misuse and abuse that freedom---requiring God to deal with it in ways that are not pleasant, ways that are regrettable, but ways that are necessary so God can carry out His larger purposes.
Didn't they go to hell, and thus infinite misery?
I do not know. I am not aware that the Bible tells us either way. Their eternal destiny is in God's hands.
But I will answer what I perceive your larger point to be, namely, that if they did end up in Hell---that this was somehow God's fault.
Anyone who winds up in Hell---is not there because God actively put them there. They are there as a result of their own choices. We create Hell through the choices we make in this life. We live in the afterlife as we lived in this life. If we hated God in this life, why would die and magically start loving Him? Why would we want to dwell with the one we hate in heaven? Hell is our own creation. The problem, of course, is that while the person cannot live with God, they cannot live without God---but they hate God--so---they create their own Hell by rejecting God. That is always their free choice. God did not force them to hate Him.
This is part of the larger problem in society today: people can't seem to make the connection between poor outcomes and poor choices. And herein lies, I think one of the major differences between liberals and conservatives.
Conservatives like me---see poor outcomes in life-----as a result of one's poor choices. Liberals on the other hand tend to view poor outcomes in life as the result of oppression. For liberals, there are only two kinds of people in this world: you are either an oppressor or you are oppressed. If you have a good life, that means someone else was oppressed in order for you have that good life. That means--the person whose life is less than ideal---has that life, not because of poor decision making and choices--but because they are oppressed.
Thus, for liberals, the idea of Hell--is a grave injustice---because the reason people are there---is not because they created it through their poor choices, their misuse and abuse of the freedom God gave them, but because God oppressed them.
Thus, maybe now you understand my position on abortion a little better? There is no such thing as an "unplanned" pregnancy--outside of rape or incest, or "unwanted pregnancy." Pregnancy is behavior based. Behaviors are the result of one's choices. The pregnancy happened because two people made a choice to engage in the act that leads to pregnancy.