I might be being cynical but I think I've seen this story play out before. Did Bluesky genuinely believe that AP wouldn't work for their use-case, or did they want to own the protocol?
From the alt text:
Initial board
- Bryan Newbold - Bluesky, protocol engineer
- Richard Barnes - Co-founder Let's Encrypt, Co-author MLS, ACME, HPKE, etc
- Wendy Seltzer - Internet Lawyer & open standards advocate
- Filippo Valsorda - Cryptographer, Go cryptography maintainer, transparency log aficionado
- Thyla van der Merwe - Cryptographer, security & privacy engineer at Google
This is on top of the IETF working group news: https://datatracker.ietf.org/wg/atp/about/