That said, no one rejoices over the death of children.
Check posts #10, #11, #12, and #14 of this thread, just for a few examples to the contrary.
That means that the presence of civilians (protected persons) does not automatically render areas occupied by combatants (which this terrorist most assuredly was, even if he calls himself a guerilla or a freedom fighter) immune from military attack.
When a combatant takes it upon himself to hide in an area occupied by civilians, that combatant is to blame for the deaths of protected persons.
At least Israel apologizes and admits that it was a mistake to kill civilians. This happens in war. The US was guilty of it during WWII--and we were purposefully targeting Dresden and Hiroshima because we felt that these horrific acts were neccessary to defeat the Axis Forces that would do so to us if they had the power. It worked. We were the victors and treated the fallen survivors with more dignity and generosity than they would have done to us if the situation were reversed.
As for Hamas and other Palestinians, they have already made it clear that they want the Jews and infidels destroyed. Like the Nazis, they throw a party and are totally unrepentant when their kind murders Israeli civilians in bed, in shopping malls, pizza parlors or during a religious celebration. Genocide and driving all of the Jews into the sea is the Palestinian's ultimate goal. Not peace. It's up to Israel to make them see otherwise. Until then, the picture is not going to be pretty.