So, a recent discussion occurred around potentially removing the timer from the nuke. The eventual decision was that it leads to unnecessary breakage.
However, as the flipside to this - if the timer isn't being removed, it makes sense to specifically add features to minimize the frustration that arises from it.
Therefore, here's the proposal: A new feature - which would not become the main method of activating the nuke - which essentially becomes a shortcut for "go back 5 seconds, start the nuke, then go forward the 5 seconds again". Of course, the "5 seconds" would be frame-perfect to the nuke's duration.
This would not truly bypass the timer as such. Physics don't change at all - it's purely a UI feature to reduce the need to time the activation of it.
Perhaps this could even be expanded to "Select a lemming; then - if such a nuke timing is possible - insert a Nuke action earlier in the replay, such that the selected lemming will complete his countdown on the current frame".