Actually, it implies the opposite.
If someone who is not a nutjob is spouting the theory it will get debunked, regardless of placement on Hacker News. If Hacker News were in the nutjob category, it would be irrelevant in the flowchart. The chart would simply point from "repeated by a nutjob"->"Am I bored?"
Hacker News only takes effect if a nutjob's theory winds up on Hacker News, which based on the chart, is more akin to "Are they a nutjob?"->"No" (but not quite the same). So, while something does not need to be on Hacker News to be debunked, placement on Hacker News will result in a theory being debunked. Thus, the article implies that Hacker News is a community made up of people who are expressly not nutjobs.
It implies that the users of HN a subset of the overall nutjob population, but one worth addressing at least ;)