Questions about Creating Planets

[Rexxx]

In Master Belisarius' AI contest my EEE uses a create planet ship. When they get the Stellar Manipulation tech they already had researched all colonization techs. They created 21 rock or ice planets (12 rock, 9 ice), the 22nd (at Last) was a Gas Giant. It was almost too late...
The description of the device says: Can create a [....] planet with a random atmosphere and type. Well, 12-9-0 doesn't look like "random".

Now my questions:
Is is actually completely random which type of planet is created?
or
Does the planet type depend on your available colonization tech? If you have only rock colonization tech a new planet will be automatically a rock planet? What if you have all colonization techs?

Let the EEE use this kind of tech without actually testing its effects. Lousy…