OK, so what does that concretely mean as a policy? "Not judge", fine - does that mean no arrests, no involuntary holds, not touching them? We used to take the view that we could confine people for things that weren't their fault when there was an overwhelming public interest (e.g. people with infectious diseases).

  By the same count we don’t judge the mentally unwell and children
  as if they’re well-functioning adults.

Sure we do (or we did up until recently). Bill Clinton famously presided over the execution of a man missing a chunk of his brain to appear tough on crime during his presidential campaign.

Children and those deemed mentally unwell in a legal sense lack various individual freedoms though. There's always some trade off.

I don't think it's that simple. No one acts 100% rationally all of the time. In this respect, addicts, children, and the mentally unwell differ from the rest of us by degree - they may have diminished responsibility for their own actions, but I don't think it makes sense to try to draw a sharp line where you're either responsible for your own actions or you're not. Recovery from addiction requires assuming responsibility for one's actions.