Lets put aside the Rothbard vs Mises view of time preference. I'm still on the side of Mises, but apparently reasonable Austrians can disagree. However...

"The hoarder isn't postponing consumption..."

Hoarding a good does provide present utility, but that is not the same as consuming it. A non-perishable good like money is not used up, or worn out, or otherwise diminished in utility when it is held. The hoarder retains the full (present and future) services of the good until it is *actually* consumed or exchanged.

Rothbard recognized that too, as you mentioned above when he refers to 3 margins, not 2; and you yourself refer to hoarding as orthogonal, which would not be the case if hoarding and consumption were identical.

"A purely psychological "orientation toward the future" that never manifests in willingness to lend isn't economically meaningful because it produces no observable market phenomena."

Hoarding is not purely psychological. Hoarding in an exchange economy reduces demand for all other goods and increases the exchange value of the hoarded good. It definitely has effects in the market. This was the point of the 2nd Mises quote in my original reply. Whether those effects are observable is not relevant to economic theory.

"The HODLer who won't lend at any rate has revealed infinite time preference in the only sense that matters economically: no offered future return compensates him for parting with present capital."

The interest rate here is undefined, not infinite. You can't infer from a refusal to exchange present for future goods that the reason was an insufficient interest rate. Observed interest rates are partially explained by time preference, but they are not identical with it, nor do they measure it. There is always an entrepreneurial component.

It's the "stay humble" part of "stay humble and stack sats."