Long Haul
One question for you would be what were the destinations on the long haul airline your wife applied to?
If they were flying over say Cuba and had to land would they automatically stamp the crews passports. So would that present a problem for the airline if afterwards she was due to fly to the USA!! With a British/EU passport you can always apply for a second passport so that any stamps in it would not stop entry into any other country.
I hope that makes sense and is only a question, not a reason for her to not get the job, but maybe something to look into!