The problem is a private community that is being closed down and moved elsewhere[1] There's no easy way short of screen scraping of backing up the posts in that community. Even without the comments. We're prepared to write code but there's no way of getting the posts in the API either. And no RSS/Atom. Yes, I've seen and starred https://code.google.com/p/google-plus-platform/issues/detail?id=639
G+ communities are a roach motel. You can check in, create content but never take it elsewhere.
G+ communities are a roach motel. You can check in, create content but never take it elsewhere.
[1]In reaction to Google's support of TPP/TTIP