I don't support capital punishment, but if I were Norwegian, I might want the laws changed to include longer time periods. But the law was followed, from what little I know, and that's the important thing. Hopefully he'll never get out. I expect he'd face a lot of problems from other prisoners as well.
You're not Norwegian. No need to change the laws when they are provisos available to keep parasites like this in prison for periods above 21 years. It works well for the society, they actually handled it very well. Not much hooplah, got on with it what they needed to and the verdict was delivered.