Velocity of LoC isn't important. Velocity of user visible improvements can matter if a project feeds off of usage and popularity. Or at least that velocity matters until the OS is capable enough to satisfy the user base.
Haiku feeds off the interest and fun it brings to its developers. If you put AI in the mix you can poison what they do for fun and sink the project.
I... Don't agree with this. If your users have followed your projects developments even remotely reasonably, you taking a few months to implement something or to figure something out is not a sign that the project is dead. It would be one thing if your project was completely inactive for like 2-3 years.