Turning Point (Quest #10507) cannot be completed

(Creating this thread so there is something to refer to later, as I don’t see any pre-existing threads for it.)

When I reached Socrethar’s Seat in Netherstorm, I found Socrethar and Kaylaan the Lost standing around doing nothing and persistently flagged as unfriendly. The Aldor NPCs were also present and idling too. I tried various tricks to get the scripted event to work, but none of which proved useful.

I’m trying to do this quest on my Scryer-aligned warrior alt for the achievement “Into the Nether”. This bug has been a problem since expansion release for The Burning Crusade. Can this quest please be removed from the criteria for “Into the Nether” at this point?