This is easily the most interesting aspect surrounding the idea of Impel Down, and it's Hannyabal's true belief that he's protecting ordinary citizens that allows him to keep getting up even as Luffy beats the shit out of him
I can be sympathetic to an extent, because Hannyabal is a victim of the World Government's propaganda machine. He is a small cog in a very big wheel and is either unaware of or does not care about the countless others that wheel crushes on a daily basis.
All he knows about Luffy is that he's a pirate, and in fairness, the vast majority of pirates throughout the series are into the whole pillage and murder thing. He has no reason to think of Luffy as the good-natured goofball we know and love. In their careers, Ace and Luffy have killed people. They are thieves, and they don't really exist within any lawful framework. I'm reminded of Ace's fight with Blackbeard, when together they end up wrecking an entire town, ruining who knows how many lives without a second thought, because they're a pair of people with supernatural abilities who happen to have beef with one another.
Is that the sort of thing that should be allowed to go on unpunished? What punitive measures are appropriate for a man like Crocodile, who upturned literally millions of lives in a bid for power, or Shiryu, who kills for the sake of killing?
These are interesting questions, but it all falls apart when you consider that no pirate in the series, from Alvida to Kaido, has institutionalized and perfected the art of pain, suffering, and death on the scale that we see in Impel Down. Hannyabal himself calls the prison a warehouse. That's not the sort of language you use when talking about people, because to the World Government and the people who work within it pirates and other criminals are less than human, the ultimate other who exist only to be punished.
That's a dangerous mindset to take, because it justifies every atrocity in the name of protecting the few who are worthy of protection. If Roger is an inhuman monster then of course his child is just as dangerous, and if his child is dangerous then it's better to target all the pregnant women just in case, and if that fails you might as well try to hunt down the baby, and when that baby who's been hated by the world since the moment he was born grows up to become a pirate it just proves that they were right from the start and you might as well torture and kill him, too.
And if a few innocents get lost in the cracks, well, that's just the price of doing business. At the end of the day it's the law itself that's important, written by those powerful enough to enforce it, and not the ordinary citizens its ostensibly there to protect. Because if criminals don't have rights, then all it takes is someone in power to wave their magic wand to declare any of those citizens to be criminals and all of a sudden they don't have rights, either. It happened on Ohara, it happens in real life, and it's why Hannyabal's idea of justice ultimately rings hollow.
