Characterizing it as a coin flip is unfair I think. If this system can promote individuals to attention out of millions of targets, telling us that this person

Characterizing it as a coin flip is unfair I think. If this system can promote individuals to attention out of millions of targets, telling us that this person out of all the millions has a 50/50 chance of being a terrorist, then that is hugely valuable information that deserves further inquiry. Now, of course we don't know how good the rate is or what other evidence they already have or what exactly a terrorist is for that matter. But in principle, you'd be throwing out a huge amount of evidence if got rid of a system that changed a target's chance from 1 in a million to 1 in 2.