Makes sense. If there is going to be an assassination attempt planned by the DS they would not be able to give him a security detail where everybody was in the plot, most of the personnel in those organizations presumably got in because they believed the image of the organization and will try their best to do what that image tells them they should be doing.

So in order to make sure they will not get in the way of the attempt too badly find out the worst ones possible for the job for that day. And because they on purpose take people who are not the best, and then presumably train them badly, even if they mostly have ones who are not dirty and will try their best they can be assured that they will have a nice selection of agents who simply are so bad at their jobs that they should not become a problem for the black hats.