Being in Canada, and in Ontario even, I'm not totally sure why this is making such a media frenzy everywhere. Because he was a soldier? Between overseas deaths and other murders in our country, they don't get a lick of publicity like this has.
One soldier being interviewed answered this pretty clearly: He said that when he goes to war (or in a country at war), he knows that there's a risk he can be killed or maimed, but it's part of his job and he knows it and accept it. It does not make it less dangerous, but he does it while being aware of it.
When a soldier gets back to his country, he comes back knowing he's now safe. I am no soldier and know none, but it's easy to understand that a soldier will suffer a LOT of stress when deployed in a country at war and that coming back to his country must be a HUGE relief. Feeling unsafe back home because of a terrorist must be hard to take.
It's still probably a very punctual act, but it's still sad and must be hard for the other soldiers. I am not pro army and much less pro war, but I still understand that all of this is not caused by the soldiers themselves and anyway Canada has never used their soldiers except to help another country or to help maintain World peace (as far as I know).