Because its a rapidly trending story about technology; twitter is a very popular platform and likely a substantial portion of the HN crowd is on it in some fashion. Same reason all the Musk-related changes to Twitter have appeared on HN really. New social networks picking up (real) traction is an extremely rare event and will always draw a series of stories in their wake.
Given Musk's direct involvement in Trump's agenda, and his previous desires to make Twitter into an everything app like WeChat, his politicization of the platform - there's an interested in where those people go.
1) People were wondering since 2022 what would happen to Twitter (and it's users) since Musk's acquisition.
2) Musk decided to become actively political and to actively change Twitter as a company and a service.
3) Bluesky had previously existed as a spiritual successor to Twitter and is now gaining steam as a true successor (Mastodon didn't really get that spike, and Threads is quite different from Twitter and heavily integrated with FB and Insta).
Does anybody else get this vibe or am I going crazy?