I just said that Cultivation could still be compatible. Well, I implied it by stating that Ruin and Preservation are compatible and opposite. I do think that Cultivation is also fundamentally opposite to Cultivation and Ruin equally. Not Honor though, as a side note.
All of the shards are compatible. In that WoB, Brandon was talking about temperaments specifically, and not literal compatibility of powers. Odium would change any temperament to one with more hatred in them, the same way that Honor would change the holder to act with more decency toward his fellow men. That doesn't mean that Honor and Odium aren't compatible, it just means that they would be as conflicting a pair as Ruin and Preservation or even Cultivation and Preservation.
Ruin wanted to create and agreed to Preservations deal because he wanted to destroy things. My point there still stands.