The authorities can choose how or whether to act on a suspicious character detected by SDSS technology. Nobody says they are going to jail a person detected with hostile intent. In fact, the system helps to detect WANTED persons before they commit the NEXT crime or TERROR act! So if a fugitive is SPOTTED among the crowd by SDSS tech, the authorities can swoon in to capture him!
If a person not on the authorities' "wanted list" is Detected by SDSS tech, he can be discreetly be detained for a round of further checks/questioning. At least, his terror/crime plans can be thwarted before he actually commits it.
Can you imagine what a safer world it would be with SDSS in use?
Drug smugglers, criminals, terrorists and even Gargamel would have to fear. But if you DO NOT have hostile intent, then you are safe!
Imagine the public places where SDSS tech can be applied for keeping homeland safe!
But best of all, SDSS can also be used for commercial purposes, to screen existing and potential company employees to prevent fraud or hostile intent towards companies.