This cannot just be a case of waving a wand around her.
It was not the metal detection wand, rather the ETD swab where you actually have to touch the person and their carry on to get a sample.
As for the minister. The screening requirements apply to her as much as anyone else although the airport may apply VIP protocols if it sees fit. What brought the ISS screeners undone was that there was a deliberate targeting of the minister rather than the random, contuous process as prescribed in the procedures covered by the legislation.