The lines right before the quote about Taravangian being being the perfect vessel for the power are :
Hatred is part of it, but the power also loves fear, shame, awe, and bravery. The power is all emotions. Taravangian was never characterized as extremely hateful when he was stupid, but compassionate. He only reads the words the surgeon said at his birth when he's smart and has no emotion. When he's filled with emotion he feels bad about how he treats the people around him when he's smart. The day he ascended he was perfectly emotional and the only hatred he felt was briefly and directed at himself. The emotion that overwhelms him and lets him kill Rayse (and it's repeated several times to make it clear) is bravery. He had reasons and excuses to hate Odium, so it would've been possible to write it so that Taravangian is full of hatred while killing Rayse. Szeth is also right there and if anyone at that moment perfectly represents Odium it would be Szeth.
The scene where Taravangian is trying to plan how to save the world and is overcome with fury ends with a visit from Cultivation and she tells him: “Come. Let me teach you about what you’ve been given. I realize the power is overwhelming, but you can control it. You can do better than Rayse ever did.” Cultivation wouldn't orchestrate to have a capable vessel take over a power that only wants to kill her. Rayse was broken at the end by losing Dalinar and being forced to agree to a contest of champions. For Cultivation, a broken Odium is better than a crafty Odium, but Passion is much better than the other two. It ends with Taravangian thinking "You have no idea what you have done.", but I think that's intentionally misleading and more ambiguous than it sounds.
There's also Roshar itself. It was created by Adonalsium with three moons (green, blue, and violet). The Eila Stele has the line "For their betrayal extended even to our gods: to spren, stone, and wind." If that was what the Singers worshiped before Cultivation and Honor came along you have the three parts of itself Adonalsium used to create Roshar. The green moon and stone for Cultivation and the blue moon and wind for Honor. Odium is associated with violet, but odium doesn't represent spren. On his final day Taravangian had such strong emotions that spren were swarming around him. If he were Passion he would fill the place of the god of spren.
The Eila Stele isn't a dry historic record, it's a polemic telling the other Singers to hate the Humans and reads as if Odium had a large part of writing it. All we could be reading is Singer Mein Kampf with no other context and deciding that Gemhearted Hitler did nothing wrong. For all we know the Humans didn't leave the Shinovar until well after the first desolation and the past started to be forgotten. It's entirely possible that the humans who wound up on Roshar were the victims of the ones on Ashyn and the First Desolation was the Singers who would go on to become the Fused attacking the Shinovar refugee camp. The fused named El was stripped of his title and rhythms for insisting the humans shouldn't be killed while Jasnah is the only human we hear talking about genocide.