Mark's says Jack received TTB approval to call this spirit distilled to 140 proof a neutral spirit. There is no TTB class/type setup for an unaged Rye Whiskey.
I say that the TTB screwed up (and not for the 1st time). The regs clearly state neutral spirits are to be distilled over 190 proof. They should not have given Jack Daniels an exception for this. Not that it will do much good, but I will file a complaint on their web based application system. Instead of giving an exception to the "class", the TTB should have given an exception to the "type" I would suggest allowing the type to be "Unaged Rye Whiskey", which makes way more sense than calling this a neutral spirit.
Mark's just speculating too and so, for that matter, is Arnett. He's a distiller, after all, not a compliance officer.
I'm trying to get an answer but the Columbus Day holiday may be working against me.