China's master plan is to hoard food, which has a very limited shelf life, let it spoil then ....... profit?
If one wanted to control the price of a commodity, one could just buy or sell commodities on an exchange without actually taking delivery or delivering the physical product. For something that has a short expiry date that seems to be the best choice, even for stuff that has no expiry date that is also probably the best choice. It is something that you or I can do over the internet, it does not need to involve the resources of a state.