Yeah, and I'll bet the odor and compounds given off by a Big Mac and Fries would totally mask a nitrate sniffing device.
And he sat in the toilet and ate half of it??
One other thing, They flew on one way tickets out and one way tickets ,on another airline, back. Why not round- trip tickets?
These dudes were on a 'dry- run' or perhaps not. They might have gotten suspicious what with the attention they caused and called it off. ( whispers from the FA, sky marshalls onboard). One of them gave a 'cut it' sign.
It could have been something simple and a lot more innocent (comparatively) ... drugs. While reading it I thought that may be an alternate explanation.
I ,despite my flippant remarks about Big Macs, believe that there is a 85% chance that this was indeed a dry run. But the whole story hinges on one womans impressions. The reactions of the crew and other passengers pass through her filter.