I've going to briefly discuss two related issues. One objection to coercive interrogation is that "torture" not only dehumanizes the informant, but dehumanizes the interrogator. "Torture" is morally corrupting. It makes the interrogator callous.
Likewise, some calumniators say eternal punishment makes God a cosmic torturer. That comparison is used by atheists, annihilationists, and universalists alike. For instance, Clark Pinnock says:
God is not a cruel and sadistic torturer as the traditional view of hell would suggest…It pictures God acting like a bloodthirsty monster who maintains an everlasting Auschwitz for his enemies whom he does not even allow to die. Four Views of Hell, W. Crockett, ed. (Zondervan 1997), 149.
i) For starters, "torture" ranges along a wide physical and psychological continuum. The term is frequently misused and trivialized.
ii) As I've often explained, I don't think hell is a torture chamber. I doubt that hell is a one-size-fits-all experience. I expect eschatological punishment is customized.
There are certainly people who richly deserved to be tortured. To be on the receiving end of what they inflicted on others. That's poetic justice.
iii) In Dante's Inferno (Cantos 21-23), the damned are tormented by demons (the Malebranche) with pitchforks. The scene is redolent with black comedy.
Of course, that's fictional. But in principle, that isn't corrupting or dehumanizing to the demonic tormenters, since they aren't human to begin with. Moreover, they are already thoroughly evil.
iv) It's true that as a rule, we should avoid activities that make us morally or emotionally jaded. However, there are exceptions. Agents sometimes have a duty to do things that may be psychologically harmful to the agent. Soldiers may be obliged to do things, to protect the innocent, that are psychologically damaging to the soldiers. Likewise, field medics may become fairly hardened to scenes of agony. Ironically, compassionate action requires them to become more emotionally detached.
To be the caregiver for a family member who is senile, has a degenerative condition, is dying of cancer, &c., is emotionally wrenching. The survivor is wounded by that searing experience. Yet it's morally incumbent to face that situation.
v) Lack of human empathy is a moral defect in psychopath or sociopath because humans are supposed to exemplify human social virtues. But an inhuman attitude is not necessarily a moral defect if the agent isn't human to begin with.
The acid-drooling extraterrestrials in the Alien franchise may seem malevolent from the standpoint of their human victims, but from their own standpoint, their actions have no more malice than a parasitoid wasp implanting a caterpillar. They don't relate to humans on a human level. They aren't the same species. There's no natural rapport.
vi) If an angel "tortured" Hitler in hell, would that be morally corrupting? To begin with, this is punitive "torture," not sadistic "torture".
In addition, since an angel isn't human, it may have no more natural sympathy for a human being than a lion has for a gazelle. Angels are so different from humans that they may have precious little frame of reference.
Not to mention that the damned aren't innocent victims.
vii) God isn't human. God is like us in some ways, but unlike us in other ways. In some respects, God is the template for humanity, but in other respects, God is a radically different kind of being.