And the situation was desperate. It was growing and something had to be done. At this point personnel was expendable, and if someone who headed up the operation decided to go herself with a team she hand-picked, who would stop her? One way or the other, we are not given that reasoning. I don't have any problem creating a realistic way for them to enter. And, frankly, the gambit succeeded. They ended up with someone coming out able to report about what was seen, which was the whole plan.
I get that it is easy to blow holes in the plot. But for me, it is never how contrived the plot was, but how well a movie makes me forget the contrivance. And this film succeeded in doing that, mostly, for me.