@downey Maybe you'd have separate settings for the social timeline and the reply access, or maybe just one (so there's a privacy cost associated with giving yourself a bigger microphone). And you could have a more public type of post (say automatically invoked when you add a hashtag) that makes that post visible and reply-able to more people.
If you see a problem post, you can see how it reached you (maybe the interface shows you the closest contacts by which it reached you), then you could...