I wasn't in Tchortist armor, but I realised what the problem was.
I cheated a bit, and approached faceless territories from the wrong direction (first run into them in Caerus)and upon detection they turned hostile.
It seems that the script for the conversation only works, if you first meet a specific group of faceless.
Anyhow, I reloaded an earlier save, approached that specific group, and it was fine.