According to MTV there’s a logical (well, sort of…) explanation for the choise of clothes:
The Octopus, The Spirits arch-enemy. “[In the comics he's] just a pair of gloves. [So we made a decision] that the Octopus has a theme of dressing the way he feels everyday, or having a theme to his day to day life and making some sense with it. It’s just an opportunity to be larger than life.”
“There’s an Asian sort of theme so we went with the samurai outfit. A whole torture scene so Frank decided, let’s go Third Reich. It’s not often you see a brother with a Nazi uniform on so it kind of worked out,” Jackson said. “There’s a really George Clintish pimped out outfit that we use with the big hat and the long coat and the whole thing.