I needed to understand the angles on Threads federation in a more rigorous way, so I took a few days to think through and write up my sense of the benefits, risks, and available risk mitigations, along with loopholes that need closing and questions to discuss with fediverse administrators.
This is a blisteringly hot subject for me, so it's hard to keep my head cool enough to understand other people's trade-offs, but I'm trying.
Thanks to @darius for talking and testing through some blocking questions—I'm putting this here instead of the main post so he doesn't get reply spammed.