But the point is, in any emergency situation, you're going to default to your training if you're acting.

Trolley problems aren't conceived as a model of an emergency situation. The emergency part is there mainly to emphasise the restricted choice. To push or not to push, there is no time for anything else. You can easily imagine a contrived trolley scenario with a plenty of time to decide.

I don't understand the analogy between trolley problems and your mortar scenario.