You're right:
The area script for AR1001 (Delryn Estate) reads:
IF
Global("AnomenIsEnemy","GLOBAL",1)
Global("AnomenThugs","AR1001",0)
THEN
RESPONSE #100
CreateCreature("anothug",[893.345],3)
CreateCreature("anothug",[696.580],6)
CreateCreature("anothug",[608.633],8)
CreateCreature("anothug",[735.231],2)
SetGlobal("AnomenThugs","AR1001",1)
END
IF
Global("AnomenIsEnemy","GLOBAL",1)
!InParty("Anomen")
Dead("Anomen")
Global("AnomenXP","AR1001",0)
THEN
RESPONSE #100
AddexperienceParty(4000)
SetGlobal("AnomenXP","AR1001",1)
END
So the variable is actually used for something.
Though I don't see why that wouldn't work everytime - only that you usually don't visit Delryn Estate if you killed Anomen previously, so it's a bit obscure to find. (And it seems strange that Anomen himself was present - he shouldn't.)