I don't think we should promote the use of this on a regular app server, given how heavy it is. I'm afraid moving it to AuthzAPI makes it too available for that. Also it pollutes the public AuthzAPI with more "similar yet different" methods. Unless we can do significant optimization by encapsulating it in AuthzAPI (e.g., if there were somehow to leverage advantages at the Cassandra or Redis level), I'd rather make it an activity-specific operation.