TeeS
You've raised a really interesting point, that is the basis of the twin engined logic.
Really for the maths (of twin helicopters) to work you need to be saving yourself from FATAL CONSEQUENCES (as JimL, (who is the (pro-twin) expert in this field) has previously explained).
People get really confused about what fatal consequences are.
They don't include 'getting wet', being late, having to camp etc
nor do they include minor mundane road traffic inconvenience.
If a safe forced landing was accomplished then it gives you the 20-20 hindsight to be able to say WITH CERTAINTY that a safe forced landing was possible (because it happened). Is it without risk? No. Is anything?