Excellent post, mostly correct, I would like to offer a minor point of correction.
Lets review the 13th, (section 1 only - section 2 says Congress can enforce section 1):
Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Pay close attention to the “involuntary servitude”. This was added for the reason of allowing VOLUNTARY service. Had it not been included, the 13th could have been interpreted to require payment for all services rendered, effectively killing off any form of community or religious service.
However, for the discussion of your points, it opens an area that has not yet been discussed. What is the law if someone WANTS to be a slave? Rare, yes, unheard of... no.
So minor nit is that in addition to the government still being permitted to be a slave owner / indentured servant / prisoner ... there exists the possibility of VOLUNTARY slavery.
You make an excellent point on the 13th amendment.
I would quibble as to whether a person wanting to be a slave (I’m talking about biblical slavery) is a rarity. I rather doubt it. Many people who, for whatever reason, just have a hard time coping with basic life decisions would love to have a kind master making all those decisions for him/her.
I’d wager that if we actually allowed time-limited, specifically enforceable labor contracts (perhaps with a few other protections within the biblical spirit) we’d have quite a number of takers.