Well when I send the guard up ahead to the warehouse through the dialogue and then move up front and kill the Sabbat before the guard reaches him, he still dies, out of sheer horror I guess (and I get Humanity loss).
-talk to guard, presence him, make him go
-move in front of him (the door closes, he stays)
-kill the Sabbat
-Jack opens the door, they both come in
-the guard dies because of... nothing funny comes in mind.