There is absolutely nothing in Islamic theology, the Koran, or the Hadith to require or even think of loving your enemy. The Koran is very specific about the actions you are supposed to take against non-believers or enemies.
This is also reiterated in the Hadith about what you can say to unbelievers (lies) in order to save your life.
He is parroting what he thinks the Christians would say, and even though he might be trying to engender those feelings within himself, they will eventually fail.
He's probably already been in contact with fellow muzzies either in Australian prisons, or those related to prisoners, and making arrangements to have this guy snuffed out. The murderer won't be safe in any Australian prison if there are muzzies there.