Queen Otohime wasn't murdered by some last-minute new villain. She was killed by Arlong.
After Fisher Tiger's death, Arlong (already known to be violent and disliking humans) takes it to another level and declares war on all humans. This declaration is known as "Arlong's Will" and serves to inspire many fishmen, including Hodi.
Otohime insists on her ideals, and this leads to her confront Arlong, which ends up with her death.
These events make Jinbei reconsider his hatred towards humans and realize all this would cause only more unnecessary deaths and pain on both sides. However, Arlong's presence in Fishmen Island is unacceptable, especially with Otohime's family still around.
Jinbei, probably because of his past relationship with Arlong, decides to banish him from the island, instead of killing/putting him into jail, at the same time striking a deal with the Marines to become a shichibukai, in a way to protect his former Sun Pirates associates and reduce the risk of an attack against Fishman Island (and to further aid Whitebeard in protecting the area).
This deal makes the locals respect Jinbei up until today, even with him becoming a "pirate" in a certain way, since his deal with the Marines guarantees more safety to the island (regardless of Whitebeard's already stated protection) and respects the late Queen's desire for peace. Hodi and his gang, on the other hand, see Jinbei's actions as a cop out and choose to follow "Arlong's Will".
Thoughts?