My gut reaction is that I have an aversion to #1 as well - but I'm not sure it's a legitimate aversion. My issue is if someone looks at the tag and sees, as noted, its MOST public usage of the tag (is the tag public? yes it is. it's public because it's on at least one public post) and assumes that means things tagged with it are common knowledge (just because it's on public posts doesn't mean it's ONLY on public posts).

I think the tag level reflecting that the *tag* is public (which it is) rather than the number of posts under it that are public, is appropriate. But I don't want people to make assumptions.

That said, they COULD just click the tag and look at the posts, see the top one is public, and assume they all are. It's not like this exposes any information or allows any assumptions someone couldn't already make if they wanted to, even without knowing how to re-style the page to see it.