@xpehbam - While I don't really care if you do or don't like Oden, I think your view of the situation is incredibly shallow and myopic. It's not wrong to say Oden is a very simple man, but that doesn't mean he's an idiot either. In your interpretation of the situation you're forgetting an incredibly important piece of the puzzle: Culture.
We can say with high certainty that there are a lot of myths, misconceptions, and fantasy with regards to actual japanese history. Those things aren't actually important here, though. What we have in Wano is a hyperbolic version of a stereotypical, and idealized, feudal Japan. Even with the added fantasy-adventure elements that are all around, this core truth should be abundantly obvious. While the exact nuances may be more obvious for native readers, the overall theme should still be obvious enough. This is a society where 'bushi' and the lifestyle of the warrior caste reign supreme. A place where honor is held in the absolute highest regard, and where lying or scheming would be deemed cowardly and dishonorable; which could result in disastrous consequences. The higher your position, the more you're expected to uphold these values. You'll notice even the yakuza in this story (and in other stories as well) also follow a strict code, even though they are quite clearly a type of criminal element.
Knowing all of this, it's really not that surprising that Oden would have expectations of them keeping their end of a deal. As the readers, we have significantly more insight of the bigger picture. For the people of Wano, Orochi and Kaido are elements that go completely against their usual way of life. Oden is definitely naive and simple, but he's also just one man; even if he's strong. The people of Wano itself are just as responsible for where things head by being complicit. Something we learn they've later realized.
It's One Piece, though. Things are always going to go to cartoonish extremes to emphasise a point. If it frustrates you that much you could just take a break for a while and come back refreshed.
Man, typing really fast sucks sometimes. You end up typing way more than you thought in just a minute or two... Soryy bout that.