That "Don't think killing someone will give you the result you want" line from page 26 really annoy me.
Monster appealing to government seems like a bad idea, especially when the latter think you should die
And it also seems like a good way to make sure the guards are even more prepared for an attack
The government kills hostile monsters for population control or the ones get too close to towns.
I assume some unlucky monsters are slain for their body parts/meat though.
Useful monsters are allowed to live like the Rock cows. Intelligent, helpful monsters become "local gods", useful tools/pets/slaves, or are even allowed to become Guards (Shock).
Those two squirrels that clean Enome's Guild house are monsters.
A talking monster that has high enough intelligence to converse would be able to negotiate with the government, the only thing that might be an issue is if a cruel, greedy (looking for glory/higher pay/promotion), or hotblooded (just wants to fight strong monsters and cares about nothing else) Guard gets to the Monster and forces them to fight.
Hades would be able to negotiate with the government with ease, he's lived among humans, understands our society, and is himself educated. He even had TWO GOVERNMENT OFFICALS willing to investigate his situation and help him.
He chose not to accept that help.
Only the old people in ONE town don't like him, they don't matter when he can go literally anywhere else and appeal to the higher governmental structure.
Even if we consider a NAMED that LOOKS like a dangerous monster:
Imagine if the Monkey King approached Kikuru's village and refused to fight and especially if he was lucky enough to be able to speak with Kikuru or the girls.
Kikuru might simply try sniping the Monkey King, but luckily for the monkey king that wouldn't work anyway, so Kikuru would be forced to listen to the Monkey King yelling that he doesn't want to engage in violence - and he would get a chance to speak.
Unfortunately the Monkey King's only option even if he did engage in conversation with humanity was
1) Be a useful tool that kills Monsters or scares them away from towns.
The government would be perfectly fine with a tool that exists to kill other monsters or scare other monsters away from human settlements. That's what a "local god" is.
Assuming Monkey King denies that (it would be mean abandoning his followers that aren't intelligent enough to avoid attacking humans) - his terms would likely be:
1) Keep all your followers in whatever land we give you, away from humanity (he'd probably lose his mountain if the mountain is useful to humanity)
2) We will tell guards to avoid your territory.
3) We will kill your followers if they attack or approach our guards/citizens.
4) If any guards attack you or your followers, you must appeal to us, if you kill/harm guards without "justification" we will declare you humanity's enemy and exterminate you.
So basically he'd be a 3rd class citizen that would have to chase away rogue hunters (trying not to harm them) from his lands and deal with discrimination + whatever additional bullshit the Government would impose on him over time... but he'd most likely be able to live if he remained peaceful and accepted the occasional deaths of his comrades. (because there will always be dipshits that will go to his territory to stir up trouble or maybe his own monster followers will be too stupid to listen or simply lose respect for him).
A sad life that he decided he didn't want - hence his entire arc.
