Is it because they are isolationists. Their fleet power is superior to mine but they are inferior economically. Having said that they have not expanded their borders at all
Unless they're xenophobe isolationists, in which case you shouldn't build in the systems adjoining their territory.
Or if they're the spiritualist faction, with designated gaia holy-worlds. They will ignore you unless you colonize one of their holy world gaias.
Awakened Empires are just all kinds of screwy since 2.0. I think something's wrong with their aggression values. And, as others have said, Awakened Xenophobes no longer care about borders, the same way Awakened Spiritualists no longer care about you touching their precious holy worlds.Sorry should have mentioned they have already awakened hence their fleet power
Edit and have cb against me