If procedurally generated terran worlds can have an inimical biosphere, please let me know and I will add a means of removing it. Thank you!
Terran planets (hab4) do not have anything in the vanilla procgen to give them the inimical condition.
They have literally nothing - blank entries, with no by-type overrides.
I'm fairly sure it's not possible in vanilla.
Unknown Skies doesn't alter the vanilla condition gens at all, so it's not that either.
No idea if Nexerelin does or not as I don't use it.
Interestingly inimical can appear almost anywhere else....
Spoiler
Hab3 worlds, Terran E, Ocean, Arid and Tundra theres a 1:10 chance of getting it.
Jungle is also a hab3, but is 'special' because it gets a 1:2 chance due to it's override.
Hab2 Desert worlds, and Hab1 Barren Deserts both get a 1:100 chance.
Frozen/Ice worlds also get 1:100, as do Cryovolcanics.
Gas giants get a 1:500 chance.
Volcanic, Barren and Toxic all get 1:1000.
Irradiated worlds get a 1:10000 chance of getting it.