If you ever think that you need to put the aircraft on the ground, the weight must never be a limiting consideration.
Some pilots seem obsessed with this question of reducing to the limited landing weight. It should not be. Indeed, it is foolish to consider it so important, as the Swissair Captain seemed so to do.
The aircraft will not sustain irreparable damage if you land at the MTOW minus what you have burned in the time it takes you to prepare for the approach. It will merely need a check from the engineers.
My sailing instructor, who knew exactly what he was talking about, once told me; the first time you think you need to put a reef in a sail is the only time to do it.
So it is with an aircraft; if you think it should be on the ground ASAP, then now is the time to prepare for an approach.
Stop using words like 'nightmare scenario' and concentrate on the facts of the situation.
Flames, smoke, dying pax, serious bomb threat.........land ASAP
Engine run down, system failure or other non-critical event, by all means reduce weight.
It is not a lottery or a gamble, it is common sense.