The case of the IDF soldiers killing hostages is a very sad one, but, yes, as Bob points out here there is some reason to suppose that the fog of war will not immediately, or ever, grant us the truth.

I believe we can imagine both cases as true and people with differing intuitions will lean toward each of them.

It is plausible that these IDF soldiers were there on the hunt to kill; it is obviously also plausible that these IDF soldiers were simply protecting themselves. The stress of war is something we have to take into account.

That said, we do hold soldiers to a higher standard. They should be trained to be able to handle these high-stress scenarios. Obviously, they will still make mistakes, but overall concerns about IDF behavior as a result of this is warranted.