Energy is right, crystal spawning isn't supposed to happen for AIs.
@Cybran, you can't, officially. You can only strongly suspect one is an AI colony because of for example an odd name, not moving ever, or spawning and dropping protection immediately with 10 units or something to that effect.
They stay in protection for, as far as I'm aware, a random period. They don't necessarily wait until the end of their protection, they can also drop protection between spawning and end of their protection period. I don't know what the exact formula for the probabilities is.
Hope that helps