I would take a rough guess that if the afterburner was shut down at point of take off it would be a very short flight ending up in the overshoot or on the end of a Martin-Baker let down, particularly with the combination of hot and high conditions and weapons/fuel load.
I imagine that it is all part of the calculated risk. At least the Tornado pilot and nav have a means of escape if they have an RPG shot off at them during take off, unlike the crew of your average C-130 or other transport aircraft.