In my current game, there is the Enigmatic Fortress on the other side of one of my neighbors right along their border with another empire. The Contingency has just spawned and one of their spawn sites is pretty much right next to the Fortress in between those two empires. I believe the Fortress is still currently alive as the system is unclaimed, but I don't have vision into the system.
Can the Contingency, or any end-game crisis really, attack and destroy a guardian alien like the Enigmatic Fortress? Or will they leave it alone so I can swing by later to claim it?