Hmm. How do you tell the difference between “most people want to kill but it’s suppressed” and “most people don’t want to kill, they just find killing very attention-grabbing”? What different predictions do these make? Maybe there’s a way to falsify one of these statements.
There’s the case of escalatory revenge raiding/killing and kin feuds, which were a historically common cause of killing—but those had to do with ingroup/outgroup dynamics. There’s also infanticide, quite common historically—that seems like a premier case of doing something you don’t want to do for other reasons. Even for state-driven wars, those were about coordination failures, and elites and societies stealing land and resources from each other, not about murder for murder’s sake.
In situations where killing is encouraged, the initial reaction is reluctance—armies have to work really hard to get their soldiers comfortable with killing, and active genocides are carried about by people in really particular circumstances, with drugs, ideology, peer pressure, and authority influencing them—and so on.
So I’m not sure that “most people harbor a desire to be mass murderers” explains this well? You argue that those situations represent a release of the “suppression”—but if the suppression is sticky, and snaps back into place when people leave the contexts where it was suppressed, I think it’s just a simpler explanation to say that people generally don’t want to kill unless they’re actively pulled into it? Otherwise you could argue anything that only occurs in humans in special situations is just a suppressed natural desire—glossolalia, self-immolation, circumcision, etc.
That makes sense. I think if OP argued that many humans have a latent desire to be a warrior, fighting for a just cause, then they’d have a stronger case. And that could still get most of the way to what they’re worried about, when it comes to asymmetric catastrophic risks!