But why look at it as a percentage of their age at all? Look at it as an absolute.
Their victim is likely physically scared for life and as the article says, definitely mentally damaged. That's a life sentence.
Because as I said earlier:
I don't think [that duration of sentence as a proportion of age is] a completely invalid assessment of sentence duration.
I'm not downplaying the impact this will have had on the victim, but the length of sentence won't lessen that impact. We aren't in a position to lock everyone away for life for crimes that could have life-long implications for the victims so there's a need to form a balance which is what sentencing guidelines do.
If there are mental health issues with any of the perpetrators then I would assume that they won't be released until that is resolved.