So their plan hinged on odd chance that someone was at the door who would let them in?
What if she had simply said NO?
Exactly my point. The success of their plan depended on not firing a shot until they had gotten upstairs to the editorial meeting. If they had “gone loud” on the street, their primary target would have escaped, and it probably would have devolved into a running gun battle on the streets of Paris, much like what happened after they left the office.
Sounds like the plan was a grenade that failed to open the door.