Despite the subject matter of Partners, I've never participated in those redemption arguments. Partially because they happen while I'm asleep, and partially because I never found the question relevant, because the situation feels like one where there is no right answer.
Let's assume the worst case scenario for the Justice Route, where common monsters are attacking accidentally and Clover figures out that it's an accident early on. It still results in a dead human at the end of it. There's some degree of active pursuit or fishing for encounters that Clover engages in during the route, which indicates a more demented state of mind, except this is in conflict with Clover's active refusal to hurt NPC's all the way into high LV, stopping with Mo in the Steamworks. But even then, the option to kill doesn't exist, only robbery. To me, this indicates that Clover isn't attacking first, but he's not avoiding conflict, either.
(In Partners, I reconciled the two behaviors as a fear response, where Clover can't stand to be in places where random encounters are active. Refusing to be a predator and refusing to be prey, which results in the macabre practice of room-clearing.)
I wouldn't really fault an adult for being terrified of getting jumped and acting like that, much less a kid. But the monsters are still largely innocent, barring active combatants like the Royal Guard (and whether or not the civilian monster supports the war and would have attacked anyway, had they recognized a human.) Beyond that, whatever peace the Justice Route gives Clover is short lived, as he falls into a malaise of fury and hatred by the time of the Steamworks. There's also the adult vs. baby-with-a-knife situation going on between Clover and random monsters at some point, where lethal retaliation becomes less and less reasonable.
But then, what does making peace look like, and how realistic is it? How does one look at a centuries' long culture of hatred and despair, and believe they are the one to fix it? Does one risk humanity's survival on this chance? In my mind, the Pacifist Route and the Justice Route represent an ill-advised, high-stakes, all-in bet on a roulette wheel, especially when Flowey's the one who makes the call on which decisions stick and which ones get nixed. Try for peace, and hope that you're not dooming your entire species? Carve your way out with uncompromising violence, and hope that you don't turn into a greater evil, in the form of a 20 LV demon? Both options scream "Bad End" to me.
I am very much digressing now, but I think that the SOUL representing justice was uniquely positioned to have a neutral route be both the canon route and the route with the best outcome. Unfortunately, Flowey terminates every neutral in the same way.