You've brought up some interesting issues. I suppose a policy statement has to define service in order to define service-learning. I hope you can find a definition that doesn't exclude advocacy.
Advocacy is an important civic skill after all.
Many educators are focused on the difference between education and advocacy because they are concerned with preserving the 'objectivity' of knowledge, ie. Maybe the policy definition process can be used as an education process for the educators on how values are an integral part of the service-learning experience. You can find them on p.255 of An Aristocracy of Everyone. Sorry, they're too long for me to type in here.