Well I didn't know it actually removes the planet from the galaxy map (or does it?). Still.. it doesn't spawn from the planet.. it spawns from the Command Station (Which is on (or actually orbiting) the planet).. but I understand what you're saying.
It does. And if you bifurcate the galaxy, it'll chain. Specifically, the half still attached to an AI homeworld will "survive."
(I believe there's a bug report around where the galaxy was split because there was an AI Home in both halves)