That is interesting to say the least. There are people claiming precious metal prices are being kept artificially low using a similar way. Formally the futures have to be settled in metal but for some reason deliveries from vaults never match (i.e., they are considerably lower) the those implied by the futures standing for delivery.

Now for that to work with BTC the futures market has to get really big (in PM they say it's like 100 future oz vs 1 real oz) and they need an unlimited bankroll. At that point one can short the hell out of the futures and cash-settle if the sell avalanche doesn't affect the price as much as required.

Not saying those "conspiracy theories about PM manipulation" are true (I have no way to know) but there is evidence that looks "quite extraordinary" to my eye.