Is there any possibility that this might affect Google search results?
Maybe its nonsense and maybe it's Google, but I'm getting the impression that Google finds less and less information pointing to the OTN forum. You are not using any robots.txt to prevent Google bots from crawling OTN, or?
By saying "have no activity" I suppose this also includes posts that have not been read by anyone, right?
And what about mentioning a post using the @ symbol? For instance Resurrect an archived discussion?