Very well written, Bryon.
However one point that you raised is different from my understanding. I am not a lawyer, but I think that one does not need intention to be proven reckless in a manslaughter case. As a reference, http://www.lawteacher.net/lecture-notes/criminal-law/invol-mans-lecture.php, “… the defendant will not have had any intention to kill …” Hence the prosecutor does not need to prove that the defendant “knowingly and purposely” committed the act.
If you can include a reference of a manslaughter case requiring the killing action to be “knowingly and purposely” committed, your argument will be stronger.
Again, congratulate you on a powerful article.