For all we know, this woman could have been ragging about what a waste it was, and how terrible that a military person in war lost his life.... a very good response to that would be, yes it is a tragedy, but this soldier was doing the duty he volunteered for... he KNEW the dangers, and he signed on anyway..
This would be a tribute to the patriotism and dedication of that soldier, and the soldier's desire to protect the rest of us.
In that case "he knew what he signed up for" would be quite a tribute to his memory.