There’s a wide gulf of distance between someone with antisocial personality disorder or psychopathy who fully intends to murder another person and someone experiencing profound psychosis to the point that they don’t even know that their own actions are real. This guy was found not guilty by reason of insanity in the first place because he’s the latter and not the former. The latter can be safe in public, if adherent to medication regimens, therapy, and monitoring. The former must be housed away from the public for life.
I say that as a healthcare professional with experience with both people who have severe psychiatric disorders and also people who are in prison. The original court found this man actually did not have murderous intent and that makes all the difference.