Shichibukai are pirate scum without the decency to even own up to admitting that's what they are. They parade around as heroes reaping whatever they can, pretending to play lackey to the government all the while doing whatever they can for themselves, same as almost any other pirate would.

I'm not a pirate. I don't kidnap and torture enemies and leave them toothless and lacking fingerprints on people's doorsteps so that they're nearly impossible to identify. I serve justice. Nothing more, nothing less.