That Time I Got Reincarnated as a Slime: Tensei shitara Slime datta Ken

[DarthEnderX]

Sure, it's different.
The thing is, Rimuru is making an example, he could probably have solved the whole thing in a different way but he doesn't want to, nor does he actually care.
That's the deal about what makes him evil in this situation and morally liable.

"It can't be helped I guess" *proceeds to slaughter the army of 20k in seconds*

No, he is wrong, it can be helped.

Can it? The "thing" he want to solve is making his friends not dead anymore.

The only way he's currently aware of doing that is becoming a Demon Lord. And that requires 10k souls.

Could he solve the ATTACK in a different way? Yes. But he can't solve the dead friends any other way.

Every nation in this fantasy world seems to have a nuke, if they don't have one, then the whole political landscape makes no sense.
It shouldn't be possibly for any country without a nuke to exist.

...you know most countries in our world don't have nukes, right? Countries that continue to exist despite not having them?

I just don't want this to be viewed as an act of last resort or some bullshit like that, because it truely wasn't and isn't.

No, it's an act of justice. He is defending his people and retaliating for an earlier attack. Could he resolve this peacefully? Probably. But these attackers don't DESERVE a peaceful resolution.

RIMURU IS THE VICTIM!!!11

Yes?