They key here has to be to ask yourself why the QRH says avoid icing conditions & come up with a plan for your individual circumstances. Does the failure mean no engine anti-ice available or is it just airframe AI? Engine AI would be required if the TAT was less than 10 degrees C but you would be unlikely to get any airframe ice above about 3 or 4 degrees.
You may not have an alternate available that you could reach without descending through icing conditions.
QRH drills will not cover all eventualities. For instance on the A320 pushing the fire pushbutton means that that bleed air is not available to the failed side wing for de-icing. So if you have to descend through heavy icing to get down what are you going to do? Stay up there until you run out of fuel - NO
. Use assymetric wing Anti-ice - NO
. Reset the fire pushbutton to restore wing anti-ice contrary to the QRH drill - may be
.
Who knows for sure? You have to be there at the time. The trouble is in your scenario you are in the sim so the training captain has already made up his mind what the right answer is.