Really ? Your use of a grinning face disgusts me. The next thing you'll be saying is that they were "only old ladies so didn't have long to live anyway ".
The "proportionate" punishment for taking a life is surely the loss of your own life. This young killer has been allowed to live. It may not be much of a life, but it's an existence, and he probably still enjoys a few moments of happiness every now and then. His victims have ceased to exist because of his actions, any sort of life he now enjoys is a privilege he denied those victims.
What is it people like you do not get about "no one is saying he does not deserve to be punished".
It is his sentence that is the issue.
Thank God we are more civilised over here.