Issue #32907: Morag Tong Assassin does nothing after killing his target and reaching the Inn of Ill Omen
After completing his assignment, he will make his way to the Inn of Ill Omen. He no longer serves any purpose (other than the valuable armor that you may covet), but he will attack any NPC that he sees.
Quote taken from: Oblivion:Morag Tong Assassin (UESP).
The problem is that once he arrives at the Inn of Ill Omen, he will stand in the same spot forever and do nothing. He has this package:
aaaDefaultExploreCurrentLoc256 [PACK:000A3A59]but this package doesn't seem to affect his life at the Inn of Ill Omen. He will not wander around at all and be completely static outside of the Inn permanently. I may be wrong, but be probably should at least wander around a little bit outside of the Inn after arriving there.