I don't think the game needs another silly mechanic like that. It's already kind of jarring to see Flechette Torpedoes delivering stress even when they haven't been fired because of Munitions Failsafe.
Is it that the Torps haven't been fired (at all) or that not ALL the Torps have been fired?
I have interpreted the Munitions Failsafe card to mean that you have not expended a FULL SALVO of Torps, as, clearly (well... at least to me...) each Ordnance card (whether Torps, Missiles or Bombs) represents more than one actual warhead.
Personally, I think the card title is a poor choice of words as it really does not equate to any common usage of the term "failsafe" that I am used to. Perhaps it would have been better as an EPT as more skilled pilots pilots could get the desired effect on target while expending fewer Torps and/or realized when they did not have an optimal shot. Either way, the effect of the card would be to reduce the "wastage" of expensive ordnance.