Changing realms is still swearing a oath, it is just a different oath to that of a estate. You have sworn allegiance to the new realm, only in the case of your character its all a sham, most likely to make it easy for your character to pass through their realm.
Well hmm, never really seen it that way myself after the recent changes. I thought that changed the way we were supposed to perceive things.
At any rate, if we're only discussing my personal character, for those that know my character from Luria I'm not so sure what they would say about his dedication to oaths anyway. Then again, IC and OOC I see it completely differently, but hey its a game.