"the hoarder isn't actually deferring consumption: they're consuming the money's services (liquidity, optionality, removal of uneasiness) in the present moment."
Are you trying to say that Mises is wrong, or that your definition of hoarding is somehow different than Mises' "plain saving"?
Assuming the latter, I think it would help clarify things if you could explain that difference in relation to a non-monetary economy. (I think you will find that there is no difference.)
"...whether it reveals time preference through the mechanism of originary interest. Mises himself defines originary interest as the discount of future goods against present goods in exchange, which hoarding by definition does not involve since no temporal exchange occurs"
But Mises does not say that originary interest is the ONLY way time preference is expressed. My first quote from HA very clearly says the opposite, in fact.