Officio Assassinorum:
Operation Assassinate: If the mission you are playing uses Victory Points, you receive
one bonus Victory Point at the end of the game if the enemy’s Warlord was removed as a
casualty as a result of a Wound inflicted by a model with this special rule.
Unfortunetly, it doesn't say "wound inflicted by a model with this special rule in this formation". What's stopping you from taking several assassin detachments (say, 10 Vindicaires) and immediately scoring 10 VP for popping the enemy warlord?