I think this is a very well constructed theory which fits in perfectly with Odium being Rayse's interpretation of the shard of passion.
One thing I don't believe we know yet however is whether the original vessels knew which shards they were going to hold, or really anything about their ascensions at all. Rather than his interpretation of the shard's intent making it a monster, I would argue that Ruin started out with more of Ati's intent (creating Scadrial with Preservation) but over time, was overcome by the shardic intent of Ruin.
We know a lot less of Rayse, but if he does indeed hold the shard of Passion, his original hatred could have been prevalent enough at the beginning of his time as a vessel to become known as Odium. He could even have named himself as such like Sazed named himself Harmony. Now, having been trapped for thousands of years, we could be seeing more of the Passion coming through as the shardic intent takes over.