The thing is about karma is that it is a samsaric phenomena - it is brought about by the ego-clinging self that is existant in samsara. Once we are liberated it can be seen that the self is a delusion as is of course karma but we have to be liberated from samsara for this to happen - until hen we are subject to the self, the ego and to karma - positive or negative. Karma is about doing or not doing harm - enlightened beings who have transcended samsara are of course not subject to this, as there is no inherent self and a complete awakening to the emptiness of all phenomena.