Kind of a question because I solved my problem but I'm scratching my head wondering, why is it so?

I have a custom faction which NPC members in the cell belong to and at some stage the player gets added to that faction. Before that I wanted the player to not own anything in that cell before becoming a member so I set the cell ownership to that faction, for whatever reason this resulted in the main (only mobile member) NPC to dump all his AI packages and follow the player around like a bad smell the moment he gained LOS with the player, WTF?