As far as I know, there is not a single response made by the devs indicating that the quest will only be offered for a limited time. However, I can see the reasoning behind this rumour:
Jane: The quest is offered by the security advisors of Queen Zhah addressing an unrest amongst Gargoyles. If Zhah acts on those Outcasts in the Abyss in a future event, this quest will likely be replaced by another or end. This is what happened in the Ranger of The Abyss and later Rise of the Bane Chosen event quests.
John: These are true. However, Ranger (and Warden, you left that out Jane) of the Abyss event quests are offered to determine who will win one of two housing plots in the Stygian Abyss. We all knew the quests will eventually end and winners will be announced. Rise of the Bane Chosen quests always end with a new Publish, so we were able to check TC1 to see the quests are no longer offered or see new quests are offered instead, at least a week prior.
fred: These are all true, but we can never be sure until a dev responds to this thread. And also, why is my name not capitalized?