I tried stealing the key from the nightkin jailer (can't do it), stealthing into the warehouse and stealing the info from the computer (harland hostile,) stealth killing the jailer for the key (nightkin hostile).
I don't know why I want to resolve this peacefully since I hate the bright brotherhood but is just struck me as odd there was no peaceful resolution to this chapter of the quest.
Was there any real benefit to helping either one? I couldn't tell. Seemed like it was best just to kill all parties for xp and loot.