"Totally removed from reality" it is, "guilt free" not necessarily.
Doom 4 being guilt free relies on three central concepts regarding morality
The problem with this is that the lore establishes that you don't have to be a terrible person to go to hell. Like, hell, the game itself throws that first point out the window in a log explaining that like, even if you're the most saintliness person ever you'll go to hell if you get killed in a satanic ritual, or if an Imp or Hell Knight kills you or something like that (the lore is pretty minimal, which c'mon it really doesn't need to be, it's Doom for christs sake.)
Thus, some of those demons you're gonna be ripping and tearing are.... well fairly decent people. Hell, I think the Cyberdemon is outright stated to be, like an ex-con who repented and become a nun but went to Hell anyways because the UAC forcibly sent her to hell so they could augment her into being the Cyberdemon, which is why it has a laser arm and shit.
I mean, it's established that the demons are more than just (figurative and sometimes literally) mindless killing machines since they have some semblance of a culture. Shit, the lore established that what demons are to humanity, the Doomslayer (Doomguy's name to the demons) is to demon society. Like, Imp parents tell their little Cacodemons "don't worry kiddo, the Doomslayer isn't real and he isn't in your closet" like how we do with the boogieman or some shit.
So the morality is a bit dubious, I guess.