there is something else...I have my doubts of his bounty raising. Pirates that go into the New World loose their bounties I think or at least they don't change anymore as bounties are useless there as they're out of the reach of the WG.
I haven't seen any pirate from the New World with a bounty, outside Rockstar and it was his former bounty (I think).
Also by now the whole world knows that Luffy is the son of Dragon and has connections (in their eyes) to the WB-pirates, Red-haired pirates and former WB-pirates and they know he actually invaded both Impel Down and Marineford (though maybe the don't know about ID) + he already had 300 million on his head.
A bounty has become pretty useless now for him.
maybe they don't know he defeated gecko moria...in horror island