Many thanks, anon. I'm totally in favour of the freedom of the individual reader to come up with a reading, so I'm a bit loathe to sway you in either direction. Also I have to read the fic again to remember what actually happens. Ah yes. What I think is that the nurse's situation is something Mulcahy's going to read as an allegory for his own: he's taken by his vocation. The nurse's fingertip bruises came from her fiance, which is why Hawkeye was concerned enough about her coming to harm at his hands when the bloke discovered the two of them together to step forward and risk a thumping himself, which is what he got. So Mulcahy's witnessing violent retribution for infidelity, and that's making him think about what he's doing. But your reading is, of course, equally valid.

(How did you even find this fic, by the way? I had to get to it via the link in the comment alert that came into my inbox - I couldn't find it in the community memories.)