He's hardly harmless. He's likely to be the next King of the Pirates if I don't stop him and that isn't something the world needs right now.

He's declared war on the World Government, broken out hundreds of very irresponsible criminals from the world's most secure prison -- including one extraordinarily dangerous ex-shichibukai he helped put in there in the first place; and he's endangered the lives of thousands of people dozens of times over and he'll continue to keep doing so until someone stops him.

It's my job, my duty, and I will see it through.