They probably did not want to “go loud” until they had slipped inside and upstairs to the editorial office. Any shots at the door on the street would have ruined the sneak attack. Many more doors would have locked inside, police would have come, etc. They had five minutes inside. Getting inside quietly was a critical part of their plan.
She allowed it.
Perhaps they had such good target information that they knew that at that time, she comes back to the office with her kid and puts in the code to open the door.
If so, very good target analysis, very good (evil) plan.
It seems to me that they had a lot of information about the office. Possibly they had simply been watching it for some time, or possibly they had someone on the inside or someone who had worked there and knew the routine.
If someone pointed a gun at my granddaughter's head and said " open the door or I'll shoot", that door is opening up faster than it takes time to say OK.
It's easy to Monday morning quarterback, but there are few here who would have done differently.
I refuse to fault her for her decision. I would have done the same.