Oh wow, it's still not over.

Answers in bold!

I understand I'm using American law here:

OdinMS distributed their source code.
-> Publishing own written code falls under the freedom of press.
-> That would be great if these people were the publishing members of a press organization.

OdinMS did distribute a new EXE which connected to their server instead of Nexon's.
->That's the main question here... did they really do that and who -exactly- did that then? It was never on their site / forum. Nexon has to -prove- it was distributed by the guys from Odin with -hard- evidence. And -that- IS going to be a very hard case to crack, if not impossible...
-> The OdinMS servers were raided. Nexon has access to all of the files the day the site was taken down

OdinMS ran its own PServer
-> Running own written server software is not illegal, as long as the server software itself is not copied from another source.
-> http://www.eff.org/cases/blizzard-v-bnetd