I dunno, if this is a bug at all bcs the secret passage is a protective mechanism against intruders like the Gobbos, and also houses the secret treasury of the Druids.
If you kill Nettie (depending on which path you take with her), no one else will become hostile when you open the Enclave Library.
The problem exists with Nettie because she is the only NPC in close proximity. If she becomes hostile, so will everyone else, unless you kill her beforehand in the room with which she continues the conversation with us and tries to poison us.
