If boss was able to insert that problem in the sim, that means the scenario is possible.
I wouldn't shut the engine down in cruise, but before the approach, definitely yes .
There are risks associated with both philosofies: if you shut it down the only risk is having an eng failure on the other one.
But if you keep it running the risks are higher: first of all you are not trained to do that; second you have no clear pattern ( for a go around, for example) with an engine which is producing a thrust which is no meat nor fish; third, when the time comes to shut it down -after touchdown at latest- better you don't make mistakes: you'll be on the grass before you realise it, and not with idle as it usually happens, but with 77% thrust on one side!
Flying a single eng approach is a piece of cake, people fly 3 hours on one engine in the middle of the ocean, but how many accidents/incidents have happened with asymmetrical high thrust?
Did boss give you such an analysis of all the risks associated in the debriefing, or just he told you "NO, do it this way!"