I don't. The context it is used in in the article (not just the reference to "chattel currency" but the reference to the user of such a currency being a "shill for the financial industry" is pretty dead on the the criticism by the subculture in which you find "chattel currency" used prior to the article makes of US Federal Reserve Notes as a scam that was promoted by the banking giants that are members of the Fed to get people to hand over their "legal tender" gold for not-legal-tender (as they claim) Federal Reserve Notes, the commissioner has just dropped bitcoin into the place of Federal Reserve Notes and the network of bitcoin miners in place of the banks that make up the Federal Reserve system.
Its not particularly plausible that the commissioner meant to say something else and it was conveniently "mistranscribed" into an attack on bitcoin that specifically uses both the terminology and the substantive logic of a attack by a subculture that has substantial overlap with the pro-bitcoin community against the trustworthiness of the US dollar and the system supporting it.
It is not a common term by any means. I find it extremely plausible that it was incorrectly transcribed in this instance.
Barring that, I find it plausible that it was picked for it's loaded connotations (If so many people have found this term objectionable, and the term is not in common usage otherwise, I find it plausible that all of the usages that you have found were picked with the common usage of "chattel" in mind. Were this a term that actually seemed to be in common usage, I would not find this to be plausible.)
The later was my knee-jerk interpretation, but I think I was wrong and my money is now on the former.
https://news.ycombinator.com/item?id=5670201