[avz]

What does "habitable" mean in the context that includes multiple alien species that evolved independently on different planets? After all, alien fishalikes that might have evolved in the methane lakes on Titan are unlikely to share our idea of "habitable"...

[narrator]

I'd imagine anything with evolved life is considered a habitable planet. The E.Ts probably have some rule that you have to mostly leave those places alone unless you've come to a fair deal with them. The fairness requirement is an obvious necessity due to the huge power imbalance between the two parties.