I'm not sure if this is the reason, but BlueSky doesn't appear to have a trust/safety moderation team that can operate at full scale. I mean, neither does twitter, but Jack understands that some people do want that. On the other hand, it's much easier for Meta to launch since they already have those people in place for Instagram and Facebook.
Moderation is a key feature of the MVP. If a horde of n-word spewing, cp posting spambots is the image that gets shared on newssites, it's dead in the water.