The banks are the govt, so whether JP Morgan is acting as an agent of the US govt or not is entirely semantics.
Silverdoctors overestimates the importance of JPMorgan's "stash"... 130m oz is nothing in the greater scheme of things
130 was the lower bound, not upper bound. Your numbers for how much above ground exists is always way off. You also never take into account how much is used by industry vs how much is mined either. There's only something like $40 billion dollars above ground that can be brought to market, but most of those people won't sell anyway. Why sell the base of Exter's pyramid? There's no point.
I tend to see the above-ground quantities instead of investor-grade silver, because metals can always be repurposed given sufficient financial incentive. Scrapping from technological components like gold-plated fingers, gold nanowire in integrated circuits and palladium in smd capacitors, is a prime example of tiny quantities that are getting recycled... obviously no-one bothers at 15$ per ounce but things change at 300-500-1000$ - even for micron-level plating (!)
The macro-object scrap market is also affected, with stuff like candlesticks, big mirrors, dining stuff (dishes, forks, spoons, etc) - where say a dish that weighs 20 ounces, at 300$ per oz, is now 6k USD. Or the whole spoon/knife/fork set might then cost 15-20k... Or entire bags of junk silver coins that would suddenly be in the 6-figure range. Is that going to happen? I wish it did but I don't think it will. And it's not even an unrealistic scenario if we factor the 50$ prices in the Hunt-squeeze-era and adjust it for inflation to today's prices to something like 200-300$, yet I don't see it happening without something dramatic like a country issuing their national currency on silver. But that would be their own undoing, since at that moment their national debt would also be repayable in ...silver. And while you can repay old bonds by printing new digits in a computer server of the central bank, you can't print silver to repay bond holders.