On Dirty Hands and thought experiments more generally

I will admit I have always found the central argument of Michael Walzer's "Political Action: On Dirty Hands" to be compelling. Morality and ethics are different, though related. One can be in a situation where there are no morally acceptable options available; one must still choose. I accept the criticism of ticking time bomb scenarios that they do not occur in real life, that torture in particular is not a reliable route to information. Indeed, the difficulty with most dirty hands scenarios is that people will, inevitably, try to make their decision into not-a-dilemma: there was really only one thing to be done, so it must be ethically and morally right, so there is no need for guilt or bad conscience. 

Over the summer I did a World War II study with my eldest child, and we ran across an example here, beginning at 47:30, about the bombing of Cleves, described by the person who ordered it. It's a pretty straightforward scenario: order the bombing of Cleves and ensure support for the Allied crossing of the Rhine (but also destroy an ancient city and certainly condemn hundreds or thousands of people to death), or decline to order it and let your own troops be killed by enemy soldiers who continue to occupy the well-defensed high ground. In the short excerpt he describes the decision, which seemed easy, and the after-effects that are still with him 20 years later: nightmares, and the feeling of being a murderer. 

Which is to say: the point of dirty hands is that you end up with dirty hands. You are free to do something immoral under duress, but the cost of is forever feeling guilty about something you cannot take back or undo (and you feel guilty because you are guilty). If you refuse, or are unable, to feel bad about what you've done, dirty hands can't apply.