It is not their larger Sil that gives them the vehicle stat line, it is the fact that the PCs are running into them in a vehicle that gives them the stat. In the follow-up to the AOR: Beginner's Game adventure the PCs can fight giant moon lizards the largest of which, while it should probably have vehicle stats does not as the PCs fight them on foot.
That makes sense.
For now... if I am building a creature that will be encountered by the PCs in a ship, I can just use the Vehicles section in the data editor.
Oggie: Any chance we could see an "Other" type in the Vehicles section.
Or a "Creature" type?
EDIT: Nevermind. I hadn't looked close enough. There's a "Space-dwelling Creature" type already listed! (I suppose one more for Planetary Creature wouldn't hurt.)
Edited by Simon Retold