i see this a lot but this is a misconception. “threadiverse” originally was a term to describe the “threaded fediverse” i.e. Reddit-like platforms like Lemmy and kbin. Bluesky and Threads are not threadiverse because they operate on the microblog model not the threaded link aggregation model. this usage has nothing to do with the then non-fediverse related Meta project “Threads” and can be seen predating it.

citations:

• June 14, 2023 first mention of “threadiverse” i can find https://lemmy.ml/post/1265079
• July 5, 2023 Meta announces Threads, reusing the name of a previously discontinued product https://about.instagram.com/blog/announcements/threads-instagram-text-feature
• March 21, 2024 Threads opens its integration to the fediverse https://engineering.fb.com/2024/03/21/networking-traffic/threads-has-entered-the-fediverse/