I've killed him 20 times as of last night since tuesday, and finally got my pieces. Seing if he was perma-camped 24/7 and we know hes not on Order at least, he had less that 50 spawns that period. I haven't seen it happen, though the last time was quicker than the usual 5 mins.. maybe 3.
Odd he would despawn so fast.. pretty sure thats all server side and the hotfix was client.