The whole, "people signed up to go to war" thing. That doesn't exist in our military.
You don't get to pick whether you go to Iraq, Afghanistan, or a Florida. You join and they send you where you're needed. Only the Army and Coast Guard have a guaranteed job selection (meaning you get to choose what you do) and even so you may still be a radio operator assigned to an infantry unit (which means people will be shooting at you).
Some guys are lucky and really good at what they do and can get assigned non-combat positions, but those are few.
A friend of mine is an aviation electrician and was assigned to a special ops support wing and got to go to England, Germany, Japan. I had another friend who was a Marine and asked to be assigned to logistics (what he did in school) but got put into the infantry, did four tours, got wounded four times before getting a medical discharge. So things are very much a lottery.
So by joining the military, you are in some way "going to war". The guys that really want to kill people and guys like the fellow from the article deserve everything the get and more. But it's a little more complicated than most would believe.