I believe the “hero” word is, as you indicate, often bandied about carelessly. In this situation, I think it refers to his several previous deployments and stellar record from those, and most importantly, that the man he was questioning had been spying and that he warned his men to change positions. Derrick’s actions helped all his men avoid being killed in an attack that resulted from the spying. The link in post 47 explains it better than I could.
Correction: the link to the explanatory article is in post 69, not 47.
None of that stands as heroic actions they are in fact patriotic. I have heroes, men you will never hear of. I know what they did and I know they did it because they loved the men they served with. They did multiple combat tours or volunteered for convoy ops out of a sense of responsibility. Most paid heavily for their patriotism. All of them would correct you if you called them heroes. Which is why I do not use the term hero lightly.