How do you feel about trolley problems generally? Horror and disgust. Then I see that even if I am not going to be in that situation, I may be in situations where I must behave rationally, and Stoically fight down emotional responses.

I think of trolley problems as being related to Newcomb's problem.

If you expect to encounter Newcomb-like problems, you change your source code to precommit yourself to one-box, even though it seems less rational. Evolution expects us to encounter trolley-like problems, and has changed our source code (that's the "horror and disgust") so that we are in some sense precommitted to not throw the switch. And in general, if you're not considering theoretical dilemmas in an armchair, there are very good reasons for that source code change.