Google thinks it knows how people's social "circles" interact. But any attempt to make people make "public" G+ posts just because content is public elsewhere hits several of the Geek Social Fallacies, notably 4 ("Friendship Is Transitive") and 5 ("Friends Do Everything Together").

That's a bit of a stretch. I don't think that's the justification Google used nor do I think that's the problem that people had with it. The real issue was that Google was forcing the link between Google+ and YouTube along with the real name baggage. Most people had a pseudonymous name on YouTube and Google decided that everyone should suddenly attach their inane YouTube comments to their real names where potential employers and relatives and anyone else could easily associate the two.

This isn't really an issue of friends, because most of the people you'd be concerned about finding your random YouTube comments are not friends. It's also not an issue of Google failing to understand this. Google understood the issue, but they denied and ignored it, choosing to force this on people regardless because they felt it was strategically useful to do so.