I haven't seen any evidence of manipulation to get Tailscale on HN, nor has it been on HN particularly much: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que.... As far as I can tell, HN readers are genuinely interested in it, partly because they know the founders, and partly because the people involved are experienced bloggers and good writers. This article, for example, seems unusually well put together. When the underlying topic is already of interest, that makes a big difference.
I have no connection to these people and still find this technology as something new and fascinating.
It's hard to see a genuinely new concept in startups these days given the million SaaS PaaS startups all clenching over low hanging fruit...