Not sure about this but intutively I can say, :roll:
If we declared business method in Home Interface of session Bean. Then bean provider need to define those method in Session Bean.In that case the specification needs to mandate the bean provider to implemenation business method in such a way that it should maintain the client specific details.(Line in the case of Stateful Session Bean client specific details are managed by container). And the client specific details are attached to the session bean but not the Session Home.
So ultimately you have to define the business method in Component interface(which extends EJBObject)
Hope it helps.....