I am sure the trend monitoring is great too - but what happens if it starts to paint an ugly picture halfway over the atlantic?
Trend monitoring is an engineering function. If I understand you correctly what you are saying is what happens if another engine starts to give concern half-way across the atlantic.
The answer is you would continue on two to the nearest suitable airport.
If you are half-way across the atlantic in a 757, 767 or 777 and an engine fails, what would you do if the remaining engine started giving cause for concern?
Similar situation. Tell me which you would rather be on board.
Regarding the interview question if it were asked there would be no right or wrong answer. What they would be interested in hearing is your analysis of the hypothetical situation they presented you with and the quality of your thinking.