Poryatown changing allegiance does not seem to me to have been a violation of the rules. Clearly there is a fairly broad understanding that prior to this event, it was not considered a bug for capitals to be able to change allegiance. I cannot think of any reason to punish the player responsible that does not involve ex post facto changes.
As to the second duchy changing allegiance, that is clearly the result of a bug. However, the intent is questionable. From comments that have been made here, it does not sound like the goal from the beginning of this chain of events was to achieve a realm merger; rather, one duke made a power play, and then the other duke responded by also switching allegiance because he felt he had no other choice if he wanted his stronghold to survive. The only real question in my mind is whether he knew that his ability to do so was the result of a bug.
