What this story makes abundantly clear is that it’s very easy for people to interpret innocent behaviour as sinister, but the flip side of this is that it’s very easy to interpret sinister behaviour as innocent.
Carrying a musical instrument case is apparently sinister, but would the writer have become concerned if she saw someone messing around with their shoe?
Two aspects of the story sound a bit suspect to me…
1) After the cabin crew had “strapped themselves in for landing” seven men stood up and stood waiting to use the lavatory but “not one of the flight attendants asked them to sit down.” Surely cabin crew would not allow this on final approach? In fact surely there isn't enough time for seven people to take it in turns to use the toilet on finals?
2) A flight attendant told the writer and her husband that there were “federal air marshals sitting all around us”. Surely cabin crew aren’t meant to tell passengers this under any circumstances?