This authorization will return true if there is implicit access (e.g., the content item is public and the user is anonymous), however there are activities that are delivered to the stream for the content item that are probably things we don't want to expose for anonymous users.

@nicolaasmatthijs @simong  I understand content members aren't Libraried right now, but are they one of the things that probably should be? In that case, we might want to secure the content item's activity stream a little tighter to it doesn't slip through the cracks when it's updated.