Just a thought here: Didn't DHS ask foreign carriers for a longer window before a plane departs a gate on a US-bound flight, so they would have time to check the pax list after everyone was boarded? And didn't the carriers (rightly) push back and say that wouldn't be practical?

Would it be too Machiavellian to think that both DHS and BA actions here were to make a point in that, um, conversation?

I can only imagine how I would feel if I was one of the hapless pawns on the flight in such a game. Especially if I was flying with small children...