Was Meredith a traitor?

In the 2013 film, The Numbers Station, Meredith is a broadcaster at the eponymous broadcast station, which is taken over by a group of armed operatives. At several points in the film, the point is made that so much of the system has been compromised that they must have had inside information. Now, it is revealed that

The man who coordinated the attack is a former agent

But I'm skeptical as it's indicated that the codes for the doors change on a regular basis. During the flashback where the bad guys are breaking in, we see that, while David is preparing to repel them, Meredith is apparently calmly broadcasting in the back, something you'd think wouldn't have been happening if she weren't expecting the attack.

Of course, Meredith's body is found near the end of the movie, but this might have been a matter of falling out among thieves once they'd gotten what they needed from her.