I'm also saying that "advocating for keeping nonviolent criminals out of prison in one context" and "advocating for the opposite in other contexts" happen to consistently to be explained by selection bias alone.
I'm all for reducing the use of prisons, and though both contribute value to society, I'm generally more interested in using prisons and the threat of prisons for rehabilitation and reintegration than for punishment and deterrence.
Having said that, non-violent isn't as interesting a measure to me as scope of impact. A CEO of a company that decides to externalize some costs by poisoning the water or air supply making the local population demonstrably sicker may not have carried a knife, but the scope of his impact could be far greater than some homeless guy who stabbed someone in the arm. The first is clearly non-violent while the second is clearly violent, but the truth is, I'd far rather see the poisoning CEO in prison than the stabby homeless guy.
Only so much flagrant cognitive dissonance can sail under the flag of "the community is not homogenous and people pick and choose where to comment".
We can pick the "law, order and punishment" route or we can pick the rehabilitation route but lets at least be consistent once we've chosen a path. Picking and choosing on a case by case basis enables all sorts of terrible miscarriages of justice.