It's surprising how much sympathy a little trendy leftist radicalism will buy you in many communities. That's doubly disturbing in this case, given that one of the two murder victims, Marcus Foster, was exactly the kind of intelligent, praiseworthy, patient reformer I would consider a prime political role model. The irrational, conspiratorial part of my mind even wonders if they shot Foster because he was busy proving that a thoughtful reformer is more effective than a crazed angry radical, and they got jealous.
There is a fundamental disconnect between why we have prisons and why we say we have prisons. On paper, at least, prisons are not there to punish, but to keep society safe by keeping violent people restrained, and to help to rehabilitate those people. Retribution does not fit into liberal legal philosophy.
And of course, in practice, prisons are there for retribution (in addition to rehabilitation, which I do also support), because when someone destroys other people's lives, there needs to be an actual punishment for that, and I think most of society agrees on that.
But the SLA members are in their sixties now. Their crimes were mired in the radicalist, rebellious psychology of youth. It's obvious to any competent psychologist or judge that they won't re-offend, and they've shown they can live peaceful lives in the interim. So the only possible reason for a harsh sentence is retribution, and our legal system can't bring itself to acknowledge that on paper. Even the obscene drug minimum sentences are (in theory) a deterrent, rather than retributive.
I do not think this approach is a good thing, though I realize that a sadistic and vindictive legal system could be (very, very) bad as well. There needs to be a balance.