So all a terrorist organization needs to do is have some of its members who have yet to commit any crimes sign up for this program. There is no way the screening is 100% perfect - there will be some false negatives, and they can be exploited.
This type of program is par for the course for the TSA: introducing yet another layer of theatrics for no meaningful security benefit. The US civil air system is still no safer than it was in 2001, and that's a crying shame.