It's not corrupted.
You cannot understand their speech if you kill them without having done the questline leading up to killing them.
anubis42 wrote:"your idea is stupid af", no, you're not only very rude and racist but you're also absolutely wrong. this is not my idea but my religion.
I could be wrong (or remembering incorrectly) but think the Foxwit/Mayor part of the dialogue related to NLC content with the Alien Invasion (either pre or post) and doesn't hold significance now.
Think she ran away because in order to destroy the Antellion, they would have to sacrifice their lives and I don't think she wanted to die? (Again could be remembering wrong.)