I went in and successfully persuaded the guard. He walked over to the side of a door and suddenly turned hostile for no reason. However, he didn't attack me at this point, even when I walked right up to him. All the doors were locked except the exit.

I went through the exit back to Lower, and was about to give up on the quest when for one reason or another, I went back in. The guard began as a blue non-hostile but quickly turned into a red hostile and attacked me.

I'm not sure what went wrong with the factions here, but I did get a message underneath the successful persuade check saying 'You have already tried this'. Suffice to say, I hadn't tried it before - it was the first dialogue option I picked and the first time I spoke to him.

The guard shouldn't move around at all; did it look like he was doing a randomwalk like a citizen?

I can attest to this, as well. Yes, he does move like a citizen. The other NPC's on this quest also cycle between red and blue. The smuggler in the alley cycles, as well. If the smuggler attacks you, Wally will also start attacking you.

Yes, he was moving like a citizen, and was pacing all around the room before I even interacted with him. It seemed as though the persuade action sent him to this particular door, I presumed to open it, though it must have been part of his random walk.

Not sure what's been fixed already, but I just did the quest, and here's what I noticed-

The guard walked around like a citizen, switching between hostile and non-hostile. He gave a conversation when non-hostile, but would not attack when hostile, even when he noticed me. When I chose the option for intimidate, he made his threat, but did not turn hostile or attack me. After waiting a few seconds, I killed him. Moving to the caches, the guards were unhostile. Even after looting all the rooms, there was not a hostile guard, so I attacked them. I do not know if this is normal for switching between hostile and neutral for NPCs, but when I attacked one of a group, the rest just walked around until I attacked them. After I killed the first one they came after me. After getting the bundle of weapons, I got a journal update, and went back to Winston, but he wouldn't let me end the quest.

[Edit: Just saw, the Ledskir Gangster NPCs are hostile to me after the quest is ended.]