Maybe you killed one soldier by accident? They should have been friendly - and opening/not opening the quarantine section plays no role.
So you didn't enter this section at all? Not even via the west side door?
Kiya

The imp was a council member afterwards - he changed sides

http://kiya1.via.t-online.de/images/Div_Antxchat.jpg

here's the conversation <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />