Why would the DA need it? It might be nice, but with implied consent and secondary security, a pax has no ability to decline the secondary pat-down screening that would actually find the weapon.

How is this different than if a pax has been SSSS'd and as part of that secondary the weapon is found? There is no fruit of the poisonous tree if the implied consent holds up. If it doesn't then the whole basis for screening will fall away.