ww1,
Yes things like that can provide a false positive - as can many other foods and freshners. As far as I know you're entitled to wait a certain amount of time, and be retested. I think on the roads downunder, you get tested when you're pulled over, can wait 5 or 10 minutes (or something) and have another test, and then you go to the station for a final test. I think it's the final test that gets used in court, but bear in mind I haven't had any of this as a real experience!
It's a shame to see professionals abuse trust like this, but unfortunately there are many types of people who fly. Is 'pulling over' a 737 taking the whole event to an extreme though? I would have thought someone could have tried to prevent them from putting themselves in that position... Then again, we don't have all the facts!
Lancer