User blog comment:Khalael/Canon Policy Discussion 1: Space Marines/@comment-2253300-20131103062707/@comment-1620907-20131103063344

I do think that it is an issue that finally needs to be resolved as currently the taboo of Loyalist Traitor Chapters has mainly been an unwritten rule that veteran users have agreed to due to long memories of past incidents. However. new users are not aware of the past tribulations with Thegreatbeing and Gobba42 so I think it should be in the policy for their benefit.

As for characters, I think they are acceptable so long as they comply with canonical events and are Horus Heresy-era ones that do not survive long. Unless they somehow end up as a dreadnought.