I don't think the author is talking about starting a computer club, they're thinking about a social club. To get people in the door at a social club you need them to think "that'll be people like me."

So "Democrat ladies who lunch and write patches for Mastodon," and "Trump supporters who drink beer and write surveillance software," or "meditation group (Haskell-only)" would work great, much better than "Your coworkers, but you've never met them before."