This version of Kun Autumnlight is still in the game post 5.4, but now only gives the quests Bloodied Skies and Mantid Under Fire. The latter quest is criteria for Spreading the Warmth.
The NPC should not be taken into account in regards to lore. (See Embodied Gloom.)
Arguments have cropped up as to whether Kun Autumnlight actually perished or not, so I'm striking the latter portion of my comment until it's cleared up.