Fight fire with fire.
Capt Claret, a good lawyer/barrister will rub his /her hands together on this stuff. CASA/Company/screeners would have to be oh so careful. I'd start the test by taking a few notes (time, date, id badge number and name) and then i'd pop straight down to the doctor to get a blood test.
Its actually got me thinking that I should find out where is the quickest place to get a blood test in each port. I know there is a doctor n site in MEL but it could get difficult at some outports. Call me paranoid but let me tell you if one does come back positive and you can't fly you might find your heart rate increase a little.
What i can't work out is how they reckon this is not going to cause a delay.