That's a good response. I can only think of all the other joys he was deprived of while undergoing treatment and knowing his death was immenent. To cross this one usually forbidden line doesn't offset the horror he must have gone through but it might have given him a small lift in the midst of his suffering and I, for one, could not hold such a thing against him.
As a Christian, I wish more people would use Scripture as a lamp instead of a sledgehammer, particularly when mercy and compassion are more sought than a lecture or a doctrinal thesis. I will not say what becomes of this child - it is God's to decide. That's what makes Him so difficult for us finite creatures to fully contemplate when we seek rigid answers.
I think those quoting scripture are using it as a lamp to see these actions in their true light. While we cannot condemn this boy's soul, we may judge the actions of the adults so long as we expect to be judged by the same set of rules.